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Worcester Bosch Boiler Fault Codes
In the unfortunate event that your Worcester Bosch boiler develops an issue, it will enter a locking or blocking condition, and fault code information will be presented on the boiler display. So that you can quickly identify what the fault code means and what should be your next course of action, we have developed the below fault code finders for the Worcester Bosch range. Just click on your boiler from the below list and then search for the fault code that your boiler is displaying or view fault codes that aren’t displayed. The fault code finder will then provide you with a diagnosis, which will assist you should you need to contact an engineer.
Worcester Bosch Greenstar 2000 Gas Boiler Fault Codes
Worcester Bosch Greenstar Si Compact Gas Boiler Fault Codes
Worcester Bosch Greenstar i Gas System Boiler Fault Codes
Worcester Bosch Greenstar 8000 Gas Boiler Fault Codes
Worcester Bosch Greenstar CDi Compact Gas Boiler Fault Codes
Worcester Bosch Greenstar CDi Highflow Gas Boiler Fault Codes
Worcester Bosch Greenstar 8000 Style Gas Boiler Fault Codes
Worcester Bosch Greenstar Heatslave II Oil Boiler Fault Codes
Worcester Bosch Greenstar 24/28/30 Gas Combi Boiler Fault Codes
Worcester Bosch Greenstar 2000 Gas Boiler Fault Codes
Fault Codes
Pump Operation and Diagnosis
Faults that are not Displayed
Fault Codes
| Fault code | Fault category | Description | Remedy |
|---|---|---|---|
| 200 | O | The device is in central heating mode. | – |
| 201 | O | The appliance is in DHW mode. | – |
| 202 | O | The appliance is in optimised switching mode: the interval for restarting the burner has not yet expired ( service function 3-b2). | – |
| 203 | O | The appliance is on standby, there is no heat demand. | – |
| 204 | O | The current flow temperature is higher than the set flow temperature. The burner has been switched off. | – |
| 207 | – | Operating pressure too low. | ▶ Fill and vent the system, check the system for leaks. ▶ Replace pressure sensor if necessary. |
| 208 | O | The appliance is in chimney sweep mode. Chimney sweep mode is deactivated automatically after 30 minutes. | – |
| 212 | – | Temperature increase for safety or flow temperature sensor too fast. | ▶ Open the shut-off valves. |
| 214 | V | The fan stops during the safety time. | ▶ Check fan, replace if necessary. ▶ Check mains voltage. |
| 215 | V | Fan too fast. | ▶ Replace fan. ▶ Mains voltage must correspond to the default value. ▶ Check PCB and fan harness, replace if necessary. |
| 224 224 | B V | Flue gas temperature limiter or heat exchanger temperature limiter has tripped. | If the blocking fault persists for a prolonged period, it becomes a locking fault. ▶ Check position of isolation valve in heating circuit, open if required. ▶ Check water pressure, if necessary top up until the preset pressure is reached. ▶ Check the temperature limiter and connecting lead of the heat exchanger for breaks, replace if required. ▶ Check the flue gas temperature limiter and the connecting lead for breaks, replace if required. ▶ Vent appliance with service function 4-A1 ( page 45). |
| 227 227 | B V | No flame detected. | After the 5th ignition attempt, the blocking fault becomes a locking fault. ▶ Check whether the gas isolator is open. ▶ Check the gas supply pressure. ▶ Check ionisation signal. ▶ Check the power supply. ▶ Check the electrodes with cable, replace if required. ▶ Check the flue system, clean or repair if required. ▶ Check gas/air ratio, adjust if necessary. ▶ Clean heat exchanger. ▶ Check the gas valve, replace if required. ▶ Check burner setting, correct if necessary. |
| 228 | V | Flame signal is present although burner is switched off. | ▶ Check if there is a flame present. ▶ Check electrodes and connecting leads, replace if required. ▶ Check the gas valve, replace if required. ▶ Check appliance electronics, replace if necessary. |
| 229 | B | Flame lost during burner operation. | ▶ Check the main shut-off valve, open if necessary. ▶ Check the appliance isolation valve, open if necessary. ▶ Measure the gas supply pressure at the rated heat input. If necessary, shut down the appliance and check the gas line. ▶ Check flame sense electrode and connecting lead, replace if required. ▶ Check venturi/injector for potential blockage. ▶ Measure the ionisation current. ▶ Check the protective conductor connection in the control unit. ▶ Check the ignition cable for damage, replace if necessary. ▶ Check functionality of gas valve and replace if necessary. ▶ Check burner setting value at rated heat input. ▶ Check burner setting value at the lowest output. ▶ Check flue system. ▶ Check combustion air supply. ▶ Check the heat exchanger on the flue gas side for deposits, clean if necessary. |
| 232 | B | Heat source locked by external switching contact. | ▶ Connect the plug for the external switching contact. ▶ Install jumper/check condensate pump according to manufacturer's specifications. ▶ Adapt switching point of the external temperature switch to the system. ▶ Replace connecting lead to the external temperature switch. ▶ Replace external temperature switch. |
| 233 | V | Fault in code plug or appliance electronics. | ▶ Check whether code plug is installed. ▶ Check appliance electronics, replace if necessary. |
| 234 | V | Electrical fault in gas valve. | ▶ Check the connecting lead, replace if required. ▶ Check the gas valve, replace if required. |
| 235 | V | Version conflict between appliance electronics and code plug. | ▶ Check software version of appliance electronics and code plug. ▶ Replace appliance electronics or code plug. |
| 237 | V | System fault. | ▶ Check and replace code plug. ▶ Check and replace the appliance electronics. |
| 238 | V | appliance electronics faulty. | ▶ Check and replace the appliance electronics. |
| 242 | V | System fault, appliance electronics. | ▶ Reset control appliance / burner control unit - factory reset. ▶ Reconnect electrical connections at control unit / burner control unit correctly. ▶ Replace the control unit/burner control unit. |
| 244 | V | System fault, appliance electronics / basic controller. | ▶ Reset control unit / burner control unit - factory reset. ▶ Reconnect electrical connections at control unit / burner control unit correctly. ▶ Replace the control unit/burner control unit. |
| 246 247 257 | – | Internal burner control fault. | ▶ Reset burner control - factory reset. ▶ Check electrical connections of burner control. ▶ Replace burner control. |
| 245 249 250 251 252 253 254 | V V V V V V V | System fault, appliance electronics. | ▶ Reset appliance electronics - factory reset. ▶ Check electrical connections. ▶ Replace the appliance electronics. |
| 256 | V | System fault, appliance electronics / basic controller. | ▶ Reset control unit / burner control unit - factory reset. ▶ Reconnect electrical connections at control unit / burner control unit correctly. ▶ Replace the control unit/burner control unit. |
| 258 | V | Internal fault in control unit. | ▶ Reset control unit - factory reset. ▶ Reconnect electrical connections at control unit correctly. ▶ Replace control unit. |
| 259 262 263 | V V V | System fault, appliance electronics. | ▶ Reset appliance electronics - factory reset. ▶ Check electrical connections. ▶ Replace the appliance electronics. |
| 264 | B | Air feed failed during operating phase. | ▶ Reconnect the fan plug properly, perform reset. ▶ Replace fan. ▶ Mains voltage must correspond to the default value. ▶ Remove any blockages in the flue system. ▶ Check venturi/injector for potential blockage. |
| 265 | BC | Heat energy demand lower than energy supplied. | – |
| 268 | – | Component test mode. | Not applicable, is status message. |
| 269 | V | Flame monitoring. | ▶ Reset appliance electronics - factory reset. ▶ Replace the appliance electronics. ▶ Check flame sense electrodes and connections. ▶ Check earth connections. |
| 270 | BC | The heat source has started up. | – |
| 273 | O | Operation interrupted: safety inspection following 24 hours of continuous operation. | – |
| 275 | O | Test code plug detected. | – |
| 281 | – | Pump stuck or running dry. | ▶ Replace the pump. ▶ Vent the system. ▶ Check operating pressure. ▶ Check low pressure switch. ▶ Check pump connections (hydraulic and electrical). |
| 305 | BC | Boiler cannot start temporarily following DHW priority. | System appliance only. |
| 306 | V | After switching gas off: Flame is detected. | ▶ Check the gas valve, replace if required. ▶ Check electrodes and connecting leads, replace if required. ▶ Replace the appliance electronics. |
| 323 | – | Control communication fault. | – |
| 328 | V | Mains voltage briefly interrupted. | ▶ Check for voltage interruption between electrical wiring system of the building and the appliance. |
| 341 | B | Heat source temperature increase too rapid. | ▶ Open isolation valves. ▶ Connect plug to pump. ▶ Replace pump. ▶ Ensure circulating pump is set on Constant speed mode - curve III. |
| 342 | BC | Temperature increase in DHW mode too rapid. | ▶ If the water pressure is too low, top up with water and vent the system. ▶ Open service valves in the cylinder charging circuit. ▶ Replace the diverter valve / cylinder primary pump. |
| 350 | B | Flow temperature sensor short circuit. | bookmark0 |
| 351 | B | Flow temperature sensor failure. | bookmark0 |
| 356 | B | Supply voltage for heat source too low. | ▶ Establish supply voltage of at least 196 VAC. |
| 357 | BC | Venting program | – |
| 358 | BC | Active anti-seizing function. | Blocking protection for the heating pump and diverter valve active |
| 360 | V | Incorrect code plug. | ▶ Check code plug, replace if necessary. |
| 362 | V | Service code plug detected. | ▶ Check code plug, replace if necessary. |
| 363 | V | System fault, appliance electronics: fault when testing the ionisation signal. | ▶ Check earthing connections. ▶ Reset appliance electronics, replace if necessary. |
| 364 | V | Solenoid valve EV2 leaking. | ▶ Check the gas valve, replace if required. ▶ Check electrodes and connecting leads, replace if required. ▶ Check and replace the appliance electronics. |
| 365 | V | Solenoid valve EV1 leaking. | ▶ Check the gas valve, replace if required. ▶ Check electrodes and connecting leads, replace if required. ▶ Check and replace the appliance electronics. |
| 604 | V | System fault, burner control unit. | ▶ Reset appliance - factory reset. ▶ If the fault persists following a reset, the burner control unit is faulty and must be replaced. |
| 810 | – | DHW temperature has not increased for 2 hours. | ▶ Prevent water from escaping. ▶ Position DHW temperature sensor correctly. ▶ If no voltage can be measured, then the MC10 control panel is faulty and must be replaced. ▶ If power is being supplied to the DHW cylinder charge pump but it is still not running, it is faulty and must be replaced. ▶ If power cannot be supplied to the DHW cylinder charge pump, then there is a problem in the cable between the control panel and pump. Check screw terminals and cables. ▶ If current is not being supplied to the 3-way valve, there is a problem in the cable between the control panel and valve. Check screw terminals and cables. ▶ If current is being supplied to the 3-way valve but it is still not working, the valve is faulty and must be replaced. ▶ If a voltage of approx. 230 V is measured at the terminals and the pump is not running, the pump is faulty and must be replaced. ▶ Eliminate all faults in the cables. Vent if necessary. ▶ Replace the pump if there are any deviations whatsoever. ▶ Set the DHW heating to “Priority”. ▶ If readings are different to the values in the table, replace the sensor. |
| 815 | R | Faulty low loss header temperature sensor. | ▶ Check the sensor port. ▶ Check the temperature sensor for incorrect installation position or breakage. |
| 1013 | R | Maximum combustion point reached. | ▶ Check plausibility of displayed cylinder temperature. ▶ Check plug-in connectors and cable harness for contact. ▶ Replace cylinder temperature sensor. |
| 1014 | – | Ionisation current is too low. | – |
| 1017 | R | Water pressure too low. | ▶ Check water pressure, if necessary top up until the preset pressure is reached. ▶ Check pressure sensor, replace if required. |
| 1018 | W | Service time expired. | ▶ Carry out maintenance. |
| 1021 | R | DHW temperature sensor faulty. | bookmark1 |
| 1022 | – | DHW temperature sensor is faulty. | – |
| 1023 | R | Maximum operation time including standby is reached. | ▶ Perform inspection. |
| 1065 | R | Pressure sensor faulty or not connected. | ▶ Check plug, connect correctly. ▶ Check pressure sensor, replace if required. ▶ Check connecting lead for breaks or short circuits, replace if required. ▶ Check and replace the appliance electronics. |
| 1068 | R | Outside temperature sensor faulty. | ▶ Remedy contact problem. ▶ Replace the sensor. |
| 1073 | R | Flow temperature sensor short circuit. | ▶ Check flow temperature sensor, replace if necessary. ▶ Check connecting lead for short circuits, replace if required. ▶ Check and replace the appliance electronics. |
| 1074 | R | No signal from the flow temperature sensor. | ▶ Check plug, connect correctly. ▶ Check flow temperature sensor, replace if necessary. ▶ Check connecting lead for breaks, replace if required. ▶ Check and replace the appliance electronics. |
| 1075 | R | Short circuit in heat exchanger temperature limiter. | ▶ Check heat exchanger temperature limiter, replace if required. ▶ Check connecting lead for short circuits, replace if required. ▶ Check and replace the appliance electronics. |
| 1076 | R | No signal from heat exchanger temperature limiter. | ▶ Check plug, connect correctly. ▶ Check heat exchanger temperature limiter, replace if required. ▶ Check connecting lead for breaks, replace if required. ▶ Check and replace the appliance electronics. |
| 2051 | – | Internal fault. | ▶ Disconnect power from the system for 30 seconds. ▶ Check and replace control unit. ▶ Notify customer service. |
| 2085 2908 | V V | Internal fault in burner control unit. | ▶ Reset appliance. ▶ If the fault persists following a reset, the burner control unit is faulty and must be replaced. |
| 2909 | – | System fault, appliance electronics / basic controller | ▶ If the fault persists following a reset, the burner control unit or Key (including interconnecting leads) is faulty and must be replaced. |
| 2910 | V | Fault in flue system. | ▶ Check whether a flue system is connected, install if required. ▶ Check for unobstructed cross-section of flue system, remove deposits if required. |
| 2911 | – | Calibration failed. | ▶ Replace faulty component. |
| 2912 | – | No flame signal during calibration. | ▶ Replace faulty component. |
| 2913 | – | Flame signal too low during calibration. | ▶ Check and replace flame sense electrodes (and interconnecting leads). |
| 2914 | – | System fault, appliance electronics. | ▶ If the fault persists following a reset, the appliance control unit is faulty and must be replaced. |
| 2915 | V | System fault, appliance electronics. | ▶ Reset appliance. ▶ If the fault persists following a reset, the control unit is faulty and must be replaced. |
| 2916 | V | System fault, appliance electronics. | ▶ Reset appliance. ▶ Trigger heat demand. ▶ End heat demand. If the fault persists, the control unit is defective and must be replaced. |
| 2917 | V | No flame signal when checking the combustion control. | ▶ Disconnect power and then reconnect. ▶ Trigger heat demand. ▶ Wait 5 minutes. ▶ If the fault re-occurs within that time, reset the appliance without disconnecting the supply voltage. This triggers a calibration of the ionisation circuits. ▶ If the fault is still present after the calibration, the control unit is faulty and must be replaced. |
| 2918 | – | Fault in the flue. | ▶ Clean the siphon and drain water out of the appliance (gas side). |
| 2920 | V | Flame monitoring fault. | ▶ Check electrodes and connecting leads, replace if required. ▶ Check earthing connections. ▶ Check appliance electronics, replace if necessary. |
| 2921 | B | The appliance is in test mode ( Menu 5, page 46). | – |
| 2922 | – | Internal burner control fault. | ▶ Check and replace control unit. |
| 2923 2924 | V V | System fault, appliance electronics. | ▶ Reset appliance - factory reset. ▶ If the fault persists following a reset, the appliance electronics are faulty and must be replaced. |
| 2925 2926 | V V | System fault, appliance electronics. | ▶ Check the gas valve, replace if required. ▶ Check appliance electronics, replace if necessary. |
| 2927 | B | No flame detected during ignition. | ▶ Check the main shut-off valve, open if necessary. ▶ Check the appliance isolation valve, open if necessary. ▶ Measure the gas supply pressure at the rated heat input. If necessary, shut down the appliance and check the gas line. ▶ Check flame sense electrode and connecting lead, replace if required. ▶ Check venturi/injector for potential blockage. ▶ Measure the ionisation current. ▶ Check the protective conductor connection in the control unit. ▶ Check the ignition cable for damage, replace if necessary. ▶ Check functionality of gas valve and replace if necessary. ▶ Check burner setting value at rated heat input. ▶ Check burner setting value at the lowest output. ▶ Check flue system. ▶ Check combustion air supply. ▶ Check the heat exchanger on the flue gas side for deposits, clean if necessary. |
| 2932 | – | Internal fault. | ▶ Restart the appliance. |
| 2928 2930 2931 2940 | V V V V | Internal fault in burner control unit. | ▶ Reset appliance - factory reset. ▶ If the fault persists following a reset, the burner control unit is faulty and must be replaced. |
| 2941 | B | Insufficient flow rate in heat source. | ▶ Check plug of flow temperature sensor, connect correctly if required. ▶ Check flow temperature sensor, replace if necessary. ▶ Check pump for blockage, clear if required. ▶ Check pump settings, correct if required. ▶ Check water pressure, if necessary top up until the preset pressure is reached. |
| 2942 | – | No fan speed feedback. | ▶ Connect plug for speed control to the fan. ▶ Connect plug for power supply to the fan. ▶ Check fan harness. ▶ Check and replace control unit. |
| 2943 | – | Mains voltage too low. | ▶ Establish supply voltage of at least 196 VAC. |
| 2945 | V | Too many short heat demands in a short time. | ▶ Reset appliance - factory reset. ▶ Increase restart blocking time. ▶ Make sure that at least one thermostatic valve is open. ▶ Check and replace faulty heating pump. ▶ Check diverter valve functionality, replace if necessary. |
| 2946 | V | Incorrect code plug. | ▶ Check code plug, replace if necessary. |
| 2947 | R | Anti-seizing function is activated. | The function stops automatically. |
| 2948 | B | No flame signal with low output. | The burner restarts automatically after purging. ▶ Check CO2 settings. |
| 2949 | B | No flame signal with high output. | The burner restarts automatically after purging. ▶ Check burner gaskets, replace if required. ▶ Check CO2 settings. |
| 2950 | B | No flame signal following starting procedure. | ▶ Check CO2 settings, adjust if necessary. ▶ Check Burner and heat exchanger gaskets ▶ Check gas pressure during burning at full load ▶ Burner restarts automatically after purging |
| 2951 | V | Loss of flame too frequent. | ▶ Refer to the blocking error(s) that lead to this locking error. Check the fault history on appliance. ▶ Possible purging of gas pipe incomplete. ▶ Could also indicate a wide variety of issues such as pipework undersized or gas pressure dropping off, incorrectly routed condense drains, incorrectly sited flues, incorrectly wired etc. |
| 2952 | V | Internal fault when testing the ionisation signal. | ▶ Restart appliance to see if problem re-occurs. ▶ If the fault remains after resetting, the burner controller (PCB) is defective |
| 2953 | B | No flame signal with low output. | The burner starts automatically after cleaning (purge).Possible cause high winds. ▶ If the fault occurs repeatedly, check the settings of the CO2 values. ▶ Check Flue integrity. ▶ Check flue terminal. |
| 2954 | B | No flame signal with high output. | Burner restarts automatically after purging. ▶ Check and replace burner gaskets. ▶ Reduce burner load. ▶ If the fault occurs repeatedly, check the settings of the CO2 values. ▶ Check Flue integrity. ▶ Check flue terminal. |
| 2955 | B | The heat source does not support the specified parameters for the hydraulic configuration. | ▶ Check hydraulic configuration, correct if necessary. ▶ Check menu L2, default setting 0 required. |
| 2956 | O | Hydraulic configuration at the heat source is activated. | – |
| 2957 2958 | V V | System fault, appliance electronics. | ▶ Reset appliance electronics. ▶ Check electrical connections. ▶ Check and replace the control unit. |
| 2959 2960 | B B | System fault, appliance electronics. | ▶ Check and replace the control unit and code plug. |
| 2961 2962 | V V | No signal from fan. | ▶ Check mains voltage to fan. ▶ Check fan harness for continuity, replace if required. ▶ Check the Pulse width modulation (PWM). ▶ Check and replace the fan. ▶ Check and replace the PCB. |
| 2963 | R | The signal from the heat exchanger temperature limiter and flow temperature sensor is outside the permissible range. | ▶ Check flow through appliance and system is filled. ▶ Check for air locks in the system. Purge if required. ▶ Check Heat exchanger sensor (primary thermistor) and plug connected to stat. ▶ Check resistance of stat. Replace if required. ▶ Check continuity of harness. Replace if required. |
| 2964 | B | Insufficient flow rate in heat exchanger. | ▶ Supply sensor is not assembled on the supply pipe. ▶ Supply sensor does not make proper contact to the supply pipe. ▶ System is not filled with water. ▶ No water flow, because CH system is closed. ▶ No water flow, because pump is not operating correctly. |
| 2965 | B | Flow temperature too high. | ▶ Check flow through appliance and system pressure. ▶ Check for air locks in the system. Purge if required. ▶ Check isolation valves. |
| 2966 | B | Flow temperature increase in heat exchanger too rapid. | ▶ Check flow through appliance and system pressure. ▶ Check for air locks in the system. Purge if required. ▶ Check isolation valves. ▶ Check pump is operating freely, check voltage to pump |
| 2967 | B | Temperature differential between flow temperature sensor and heat exchanger temperature limiter is too great. | ▶ Check flow through appliance and system filled. ▶ Check for air locks in the system. Purge if required. ▶ Check isolation valves. ▶ Check pump is operating, check voltage to pump. ▶ Check heat exchanger sensor and flow sensor are making contact with the pipe work. ▶ Check heat exchanger sensor and resistance of stat. replace if required. ▶ Check continuity of harness. Replace if required. |
| 2968 | – | Refilling of system in progress. | Not applicable in the UK/IE |
| 2969 | – | Maximum number of refills reached. | Not applicable in the UK/IE |
| 2971 | V | Operating pressure too low. | ▶ Vent the heating system. ▶ Check water pressure, if necessary top up the system pressure. ▶ Check pressure sensor, replace if required. |
| 2972 | V | Mains voltage too low. | ▶ Check mains supply voltage on appliance L and N connections. |
| 2973 | – | System fault, appliance electronics / basic controller | ▶ Perform reset - factory reset. ▶ Check and replace control unit. |
| 2974 | – | Internal error | ▶ Restart the appliance and check if fault remains. ▶ Check and replace control unit. |
Pump Operation and Diagnosis
| LED colour | Description | Diagnostic | Potential cause | Remedy |
|---|---|---|---|---|
| Green - continuous | Normal operation | Pump runs as expected | Normal operation | -- |
| Green/Red - blinking | Warning mode (pump operating in an abnormal condition, no risk for the pump functionality). | The pump is running but sent a warning message. | • Dry run: – The pump is operating without water. | ▶ Check appliance system pressure and top up as required. |
| • Overload of motor: – Friction due to particles and /or impeller blocked with debris and /or too high viscosity. | ▶ Check installation water quality, clean system if debris is present. | |||
| • Generator operation: – The pump rotor is driven by an external flow. | ▶ The pump will operate normally when the external flow will be stopped. | |||
| Red - blinking | Abnormal running mode (pump stopped but still functioning). | The pump has stopped due to external failure. The pump will restart itself after the disappearance of the external failure. | • Under or Over voltage: – Mains supply voltage U<160V or U>280V. | ▶ Check mains voltage supply to pump: 160V < U < 280V. |
| • Overload of motor: – Friction due to particles and/ or impeller blocked with debris and/or too high viscosity. | ▶ Check installation water quality, clean system if debris. | |||
| • Over speed: – The pump rotor is driven by an external flow above the maximum allowed value. | ▶ Ensure that there is no other external flow (additional secondary pump running) on the system. | |||
| • Over current: – Abnormal current exceeding the limit. | ▶ Check for leakage on appliance. | |||
| • Module over temperature: – Temperature inside the motor is too high. | ▶ Check for evidence of dry running, low system pressure and ambient temperature. | |||
| • Turbine mode: – The pump is driven by external flow (>1200l/h) in opposite direction of its flow. | ▶ Ensure that the external flow is less than 1200l/h. | |||
| Red - continuous | Pump stopped | The pump has stopped due to permanent failure. | • Faulty electronic module and/or faulty motor. | ▶ Restart the appliance and wait 30 seconds before switching back ON. ▶ Replace pump if LED is still red after power restart. |
| No LED | No power supply | No voltage on electronics | • Pump is not connected to mains supply | ▶ Check cable connection and supply to pump. |
| • Faulty LED | ▶ Check if pump is running. | |||
| • Faulty electronics | ▶ Replace pump. |
Faults that are not Displayed
| Appliance faults | Remedy |
| Combustion noises too loud; rumbling noises | ▶ Check the gas type. ▶ Check the gas supply pressure. ▶ Check the flue system; clean or repair if required. ▶ Check the gas/air ratio. ▶ Check the ratio control valve; replace if required. ▶ Check condense drain is clear. ▶ Check fan depression. |
| Flow noises | ▶ Set the pump rate or pump characteristic map correctly and match to the maximum output. |
| Heat-up takes too long. | ▶ Set the pump rate or pump characteristic map correctly and match to the maximum output. ▶ Check system is balanced. ▶ Check anti-cycle time. |
| Flue gas values incorrect; CO content too high. | ▶ Check the gas type. ▶ Check the gas supply pressure. ▶ Check the flue system; clean or repair if required. ▶ Check the gas/air ratio. ▶ Check the ratio control valve; replace if required. |
| Delayed ignition, poor ignition. | ▶ Check the ignition transformer function for misfiring in Menu 6, replace if required. ▶ Check the gas type. ▶ Check the gas supply pressure. ▶ Check operation of meter governor. ▶ Check the power supply. ▶ Check the electrodes; replace if required. ▶ Check the flue system; clean or repair if required. ▶ Check the gas/air ratio. ▶ Check the burner, replace if required. ▶ Check the air/gas ratio control valve; replace if required. |
| Condensate in air box | ▶ Check the non-return valve in the air/gas manifold, replace if required. |
| No hot water. | ▶ Check the turbine, replace if required. ▶ Check diverter valve ▶ Check for cross-piping. |
| DHW volume is not reached. | ▶ Check the plate heat exchanger. ▶ Check flow device. ▶ Check silencer body. |
| No function, the display remains dark. | ▶ Check the electrical wiring for damage. ▶ Replace defective cables. ▶ Check the fuse, replace if required. |
Worcester Bosch Greenstar Si Compact Gas Boiler Fault Codes
| FAULT CODES Should a fault develop with this boiler (or the system), the boiler will enter a locking or blocking condition, and fault code information will be generated as described in this section. | ||||
| Locking error | The boiler display will flash a warning triangle and fault code. At the same time, a (static) cause code will also be displayed. Manual intervention is required following clearance of the fault: ▶ Press the reset button on the boiler fascia | |||
| Blocking error | The boiler will stop operating with no-fault data displayed. The cause code, in the info menu, is accessed by pressing the spanner/ return button. The condition will clear automatically when the associated fault clears e.g. waiting for an area to cool. In some cases a blocking error has a defined time duration prior to changing to a locking condition. | |||
| Fault code | Alphanumeric code indicating the fault group | |||
| Cause code | Three-digit number. During a blocking error (or normal operating status) it is not displayed but accessed in the info menu via the spanner/return button. During a locking error, the cause code flashes on the display. | |||
| Maintenance codes | These are displayed with the letter H followed by a number. The code advises of a situation that will need some attention but is not a fault that will stop the boiler from functioning. Some of the common ones are listed: | |||
| H11 H13 | Hot water outlet sensor defect, hot water can still be delivered but with less control (sensor open/short circuit or out of position) A time has been set in the Service interval function i.e. 1 to 72 months and that time has expired. Menu 2.5F allows this feature to be set (1 to 72), a 0 will disable this function. | |||
Worcester Greenstar Si Compact Gas Boiler Locking Errors
Worcester Greenstar Si Compact Gas Boiler Blocking Errors
Worcester Greenstar Si Compact Gas Boiler Locking Errors
| Fault codes | Cause codes | Description | Reset type | Possible cause |
|---|---|---|---|---|
| 9A | 362 | HCM (Heat Control Module) | Reset button | Incorrect HCM fitted |
| 9U | 233 | HCM (Heat Control Module) | Reset button | Problem with the code plug (faulty or not connected) |
| b7 | 257 | Internal error | Replace control board. | |
| C6 | 215 | Fan problem | Reset button | Fan running too fast |
| 216 | Fan problem | Reset button | Fan running too slow | |
| C7 | 214 | Fan problem | Reset button | Fan not running |
| 217 | No airflow after a defined period of time | Reset button | Fan not running or airflow blocked | |
| D1 | 240 | Return sensor error | Reset button | Sensor wet or damaged (the boiler will block for 300 seconds before this condition). |
| 241 | Return sensor error | Reset button | Sensor disconnected or damaged (the boiler will block for 300 seconds before this condition). | |
| 286 | Return temperature too high | Reset button | Boiler overheat | |
| E2 | 222 | Flow sensor short circuit | Reset button | Flow sensor shorted or damaged. |
| 223 | Flow sensor open circuit | Reset button | Flow sensor disconnected or damaged. | |
| E5 | 218 | Flow temperature too high | Reset button | Primary flow sensor overheated |
| 332 | Primary flow sensor has exceeded 110°C | Reset button | Primary flow sensor overheated | |
| E9 | 219 | Safety sensor temperature too high | Reset button | The main heat exchanger has overheated. Maximum temperature 105C° |
| 220 | Safety sensor short circuit | Reset button | Maximum temperature sensor on the main heat exchanger has failed. | |
| 221 | Safety sensor open circuit | Reset button | Maximum temperature sensor on the main heat exchanger has not been recognised. | |
| 224 | Max temperature thermostat activated | Reset button | Flue gas thermostat overheat | |
| EA | 227 | No flame detected after ignition | Reset button | Failure of four ignition attempts. The boiler waits 30 seconds before another attempt is made. |
| 229 | Loss of flame signal during operation | Reset button | An established flame has been extinguished. This could be caused by: • moisture in the sump, due to a blocked sump/condensate trap. • a strong wind into the flue. | |
| 234 | Gas valve error | Reset button | Gas valve coil disconnected | |
| 261 | Ignition timing error | Reset button | Flame not established during the first 4 seconds ignition period. | |
| F0 | 237 - | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | |
| 239 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 242 - | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 256 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 258 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 259 262 263 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 267 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 272 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 279 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 290 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 278 | Sensor test failed | Reset button | On power up all safety sensors are checked. Check has failed. | |
| 280 | Recycle time error | Reset button | After the burner has stopped, the recycle mode purges gas from the heat exchanger before attempting to burn again. The software has 3.1 seconds to intervene before the boiler goes into this fault condition. | |
| 338 | Too many short burner starts without confirmation | Reset button | There is an error where the pump is not detecting water. | |
| F7 | 228 | Flame error | Reset button | False flame. Flame detected before burner start. |
| 328 | Internal error | Replace control board | ||
| FA | 306 | False flame error | Reset button | Flame detected after burner stop |
| FD | 231 | Mains power error | Reset button | Electrical power interruption. |
| FA | 364 | Gas valve EV2 leak test failed | Reset button | Gas valve leak. |
| Fb | 365 | Gas valve EV1 leak test failed | Reset button | Gas valve leak. |
Worcester Greenstar Si Compact Gas Boiler Blocking Errors
| Fault code | Cause code | Description | Possible cause |
|---|---|---|---|
| A1 | 281 | Pump stuck or running in air | Little or no water in the system. |
| C1 | 264 | Airflow stopped during operation | Fan has stopped. |
| C4 | 273 | Airflow present during last 24 hours | Fan has been running continuously during the past 24 hours. |
| D1 | 240 | Return sensor short circuit | |
| 241 | Return sensor disconnected | ||
| D4 | 271 | Temperature difference between flow and safety sensors exceeds limit | The temperature of the primary flow and the safety sensor on the WB7 should be within 15°C of each other. |
| E9 | 224 | MAX thermostat activated | Flue gas thermostat overheat. |
| 276 | Flow temperature exceeds 95°C | Primary overheat - boiler waits for temperature to reduce; if not it becomes a Locking error. | |
| 277 | Safety temperature exceeds 95°C | Main heat exchanger safety sensor overheat - boiler will wait for the temperature to reduce; if not it becomes a Locking error 219. | |
| 285 | Return temperature exceeds 95°C | The boiler will stop the burn and wait to see if it cools down. If after 2 seconds there is an increase in temperature the boiler will go to Locking error 286. | |
| EA | 227 | No ionisation detected after ignition | No flame is detected. The boiler will block during 4 attempts before going to Locking fault. |
| EF | 349 | Central heating, boil detect. Large delta T despite minimum burner. | The boiler is operating at minimum burner load and there is a greater than 18°C Flow & Return temperature difference. |
| No code | 212 | Safety or flow temperature rises too fast | Air lock or reduced water content. |
| 213 | Temperature difference between supply and return exceeding limit | Air lock or reduced water content. | |
| 260 | No temperature rise after burner starts | Sensor disconnected or no water content. | |
| 380 | Inlet DHW temperature higher than the DHW outlet temperature. | The output is blocked until the inlet temperature drops below the output temperature. |
Worcester Bosch Greenstar i Gas System Boiler Fault Codes
| FAULT CODES Should a fault develop with this boiler (or the system), the boiler will enter a locking or blocking condition, and fault code information will be generated as described in this section. | ||||
| Locking error | The boiler display will flash a warning triangle and fault code. At the same time a (static) cause code will also be displayed. Manual intervention is required following clearance of the fault: ▶ Press the reset button on the boiler fascia | |||
| Blocking error | The boiler will stop operating with no fault data displayed. The cause code, in the info menu, is accessed by pressing the spanner/ return button. The condition will clear automatically when the associated fault clears e.g. waiting for an area to cool. In some cases a blocking error has a defined time duration prior to changing to a locking condition. | |||
| Fault code | Alpha numeric code indicating the fault group | |||
| Cause code | Three digit number. During a blocking error (or normal operating status) it is not displayed, but accessed in the info menu via the spanner/return button. During a locking error the cause code flashes on the display. | |||
| Maintenance codes | These are displayed with the letter H followed by a number. The code advises of a situation that will need some attention but is not a fault that will stop the boiler from functioning. Some of the common ones are listed: | |||
| H11 H13 | Hot water outlet sensor defect, hot water can still be delivered but with less control (sensor open/short circuit or out of position) A time has been set in the Service interval function i.e. 1 to 72 months and that time has expired. Menu 2.5F allows this feature to be set (1 to 72), a 0 will disable this function. | |||
Worcester Bosch Greenstar i Gas System Boiler Locking Errors
Worcester Bosch Greenstar i Gas System Boiler Blocking Errors
Worcester Bosch Greenstar i Gas System Boiler Locking Errors
| Fault codes | Cause codes | Description | Reset type | Possible cause |
|---|---|---|---|---|
| 9A | 362 | HCM (Heat Control Module) | Reset button | Incorrect HCM fitted |
| 9U | 233 | HCM (Heat Control Module) | Reset button | Problem with the code plug (faulty or not connected) |
| b7 | 257 | Internal error | Replace control board. | |
| C6 | 215 | Fan problem | Reset button | Fan running too fast |
| 216 | Fan problem | Reset button | Fan running too slow | |
| C7 | 214 | Fan problem | Reset button | Fan not running |
| 217 | No airflow after a defined period of time | Reset button | Fan not running or airflow blocked | |
| D1 | 240 | Return sensor error | Reset button | Sensor wet or damaged (the boiler will block for 300 seconds before this condition). |
| 241 | Return sensor error | Reset button | Sensor disconnected or damaged (the boiler will block for 300 seconds before this condition). | |
| 286 | Return temperature too high | Reset button | Boiler overheat | |
| E2 | 222 | Flow sensor short circuit | Reset button | Flow sensor shorted or damaged. |
| 223 | Flow sensor open circuit | Reset button | Flow sensor disconnected or damaged. | |
| E5 | 218 | Flow temperature too high | Reset button | Primary flow sensor overheated |
| 332 | Primary flow sensor has exceeded 110°C | Reset button | Primary flow sensor overheated | |
| E9 | 219 | Safety sensor temperature too high | Reset button | The main heat exchanger has overheated. Maximum temperature 105C° |
| 220 | Safety sensor short circuit | Reset button | Maximum temperature sensor on the main heat exchanger has failed. | |
| 221 | Safety sensor open circuit | Reset button | Maximum temperature sensor on the main heat exchanger has not been recognised. | |
| 224 | Max temperature thermostat activated | Reset button | Flue gas thermostat overheat | |
| EA | 227 | No flame detected after ignition | Reset button | Failure of four ignition attempts. The boiler waits 30 seconds before another attempt is made. |
| 229 | Loss of flame signal during operation | Reset button | An established flame has been extinguished. This could be caused by: • moisture in the sump, due to a blocked sump/condensate trap. • a strong wind into the flue. | |
| 234 | Gas valve error | Reset button | Gas valve coil disconnected | |
| 261 | Ignition timing error | Reset button | Flame not established during the first 4 seconds ignition period. | |
| F0 | 237 - | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | |
| 239 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 242 - | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 256 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 258 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 259 262 263 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 267 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 272 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 279 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 290 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 278 | Sensor test failed | Reset button | On power up all safety sensors are checked. Check has failed. | |
| 280 | Recycle time error | Reset button | After the burner has stopped, the recycle mode purges gas from the heat exchanger before attempting to burn again. The software has 3.1 seconds to intervene before the boiler goes into this fault condition. | |
| 338 | Too many short burner starts without confirmation | Reset button | There is an error where the pump is not detecting water. | |
| F7 | 228 | Flame error | Reset button | False flame. Flame detected before burner start. |
| 328 | Internal error | Replace control board | ||
| FA | 306 | False flame error | Reset button | Flame detected after burner stop |
| FD | 231 | Mains power error | Reset button | Electrical power interruption. |
| FA | 364 | Gas valve EV2 leak test failed | Reset button | Gas valve leak. |
| Fb | 365 | Gas valve EV1 leak test failed | Reset button | Gas valve leak. |
Worcester Bosch Greenstar i Gas System Boiler Blocking Errors
| Fault code | Cause code | Description | Possible cause |
|---|---|---|---|
| A1 | 281 | Pump stuck or running in air | Little or no water in the system. |
| C1 | 264 | Airflow stopped during operation | Fan has stopped. |
| C4 | 273 | Airflow present during last 24 hours | Fan has been running continuously during the past 24 hours. |
| D1 | 240 | Return sensor short circuit | |
| 241 | Return sensor disconnected | ||
| D4 | 271 | Temperature difference between flow and safety sensors exceeds limit | The temperature of the primary flow and the safety sensor on the WB7 should be within 15°C of each other. |
| E9 | 224 | MAX thermostat activated | Flue gas thermostat overheat. |
| 276 | Flow temperature exceeds 95°C | Primary overheat - boiler waits for temperature to reduce; if not it becomes a Locking error. | |
| 277 | Safety temperature exceeds 95°C | Main heat exchanger safety sensor overheat - boiler will wait for the temperature to reduce; if not it becomes a Locking error 219. | |
| 285 | Return temperature exceeds 95°C | The boiler will stop the burn and wait to see if it cools down. If after 2 seconds there is an increase in temperature the boiler will go to Locking error 286. | |
| EA | 227 | No ionisation detected after ignition | No flame is detected. The boiler will block during 4 attempts before going to Locking fault. |
| EF | 349 | Central heating, boil detect. Large delta T despite minimum burner. | The boiler is operating at minimum burner load and there is a greater than 18°C Flow & Return temperature difference. |
| No code | 212 | Safety or flow temperature rises too fast | Air lock or reduced water content. |
| 213 | Temperature difference between supply and return exceeding limit | Air lock or reduced water content. | |
| 260 | No temperature rise after burner starts | Sensor disconnected or no water content. | |
| 380 | Inlet DHW temperature higher than the DHW outlet temperature. | The output is blocked until the inlet temperature drops below the output temperature. |
Worcester Bosch Greenstar 8000 Gas Boiler Fault Codes
Fault Codes
| Fault code | Fault category | Description | Remedy |
|---|---|---|---|
| 200 | O | Boiler in heating mode | Operating message, is not a fault. |
| 201 | O | Boiler in hot water mode | Operating message, is not a fault. |
| 202 | O | Boiler in anti-cycle mode | Operating message, is not a fault. |
| 203 | O | Boiler in standby, no heat energy demand | Operating message, is not a fault. |
| 204 | O | Current prim. water temp. higher than set val. | The actual boiler water temperature is higher than the target boiler water temperature. The boiler is switched off. |
| 208 | O | Chimney sweep demand | Operating message, is not a fault. |
| 214 | V | Fan shut down during safety time | 1. Reset the appliance. 2. Create a heat demand does the boiler fire up. 3. Check the voltage to the fan and the continuity of the fan harness. 4. Check the power modulation on the fan. 5. PCB is may be defective. |
| 224 | V | Safety temp. limiter has tripped | 1. Check if lead disconnected from the safety temperature limiter. 2. Check the high limit of the safety temperature limiter and the harness for continuity. 3. Check the flow temperature to confirm actual temperature (may tripped out at lower temperature, leading to safety temperature limiter fault) 4. Check the system pressure and top up as required. 5. Check if air trapped in the system and in the boiler. 6. Pump seized/not running: check the pump for failure or if she blocked. 7. Check if blockage/restriction within boiler/pipe work restricting the flow. |
| 227 | V | No flame signal after ignition | Tip: Check the ceramic insulator is not damaged, this can cause the spark to earth, twist and pull the ceramic insulator to ensure it is not broken. 1. Check the gas supply to property and the inlet on the gas valve. 2. Check the low pressure when the gas valve opens. 3. Gas valve failing to open: check for voltage to the valve and for possible blockage on inlet filter of the gas valve. 4. Obstruction in the air intake to the fan leading to incorrect CO2 ratio. Diaphragm is damaged or stucked. 5. Condensate trap is blocked or restricted. Condensate pipe is frozen. 6. Flue is blocked or restricted. 7. Heat exchanger is blocked or restricted. 8. Check the burner for damage. 9. Check the spark electrode or the lead failure. 10.Check the flame sense or the lead failure. 11.Check the rectification ground (black wire to heat exchanger). |
| 228 | V | Flame signal without flame present | Tip: Check the ceramic insulator is not damaged, this can cause the spark to earth, twist and pull the ceramic insulator to ensure it is not broken. 1. Check the flame sense and the lead and replace if required. 2. Check the earth tags on the boiler and on the electrodes. 3. Check the operation of the siphon and no water collecting in the sump. 4. Replace the air and/or gas ratio control valve. 5. Replace the control unit and/or burner control unit. |
| 229 | B | Flame failed during burner operation | Tip: Check the ceramic insulator is not damaged, this can cause the spark to earth, twist and pull the ceramic insulator to ensure it is not broken. 1. Check the gas supply to the property and check the working pressure on the gas valve inlet. 2. Check the gas-air ratio. 3. Check the ionisation electrode and the harness for damage or contamination. 4. LPG: Sufficient gas in the tank or recently refilled? |
| 232 | B | Boiler locked by external switching contact | External cut off switch not used in UK: Ensure nothing is plugged into red I3 connection. 1. Connection plug for external switch contact is not plugged into PCB. 2. There is no feedback voltage at the external safety contact at the condensate lifting pump blocks the heat generator. 3. Switching point for the external temperature monitor is set too low. 4. Connection cable to the external temperature monitor is damaged. 5. External temperature monitor is defective. |
| 233 | V | Boiler identification module or device electronics faulty | 1. Wrong code plug is inserted. 2. Check the code plug is not damaged. 3. Replace the code plug if required. |
| 234 | V | Gas valve electrical fault | 1. Check the gas supply to the property and the inlet on the gas valve (check drop on inlet). 2. Check the connections on the gas valve and the board (loose connection). 3. Check the continuity down harness and replace if required. 4. Check the voltage to the gas valve (19‒24 V DC approx. when demand). 5. Check for water on the gas valve connections. 6. Check the resistance on the gas valve (pins 1‒2 approx. 69, 5 Ohms). 7. Replace the gas valve if resistances are incorrect. 8. If all tests are correct: replace the PCB. |
| 235 | V | Conflicting versions of boiler electr. And boiler identification | Replace the code plug or the burner control. |
| 237 | V | System fault | 1. Check the code plug is not damaged. 2. Replace the code plug if required. 3. Replace the control unit (PCB). |
| 238 | V | Boiler electronics faulty | 1. Check the gas supply to the property and the inlet on the gas valve (check drop on inlet). 2. Check the connections on the gas valve and the board (loose connection). 3. Check the continuity down harness and replace if required. 4. Check the voltage to the gas valve (19‒24 V DC approx. when demand). 5. Check for water on the gas valve connections. 6. Check the resistance on the gas valve (pins 1‒2 approx. 69, 5 Ohms). 7. If all tests are correct: replace the PCB. |
| 245 | State out of range | 1. Restart the appliance to see if the problem re-occurs. 2. Check the electrical connections on the board (check for loose wires etc.). 3. Check the code plug is not damaged. 4. Replace the code plug if required. 5. Replace the control unit (PCB). | |
| 249 | V | Internal software error | 1. Restart the appliance to see if the problem re-occurs. 2. Check the electrical connections on the board (check for loose wires etc.). 3. Check the code plug is not damaged. 4. Replace the code plug if required. 5. Replace the control unit (PCB). |
| 250 | V | Default software error | 1. Restart the appliance to see if problem re-occurs. 2. Check the electrical connections on the board (check for loose wires etc.). 3. Check the code plug is not damaged. 4. Replace the code plug if required. 5. Replace the control unit (PCB). |
| 251 | V | Flash test error | 1. Restart the appliance to see if the problem re-occurs. 2. Check the electrical connections on the board (check for loose wires etc.). 3. Check the code plug is not damaged. 4. Replace the code plug if required. 5. Replace the control unit (PCB). |
| 252 | V | Stack overflow | 1. Restart the appliance to see if the problem re-occurs. 2. Check the electrical connections on the board (check for loose wires etc.). 3. Check the code plug is not damaged. 4. Replace the code plug if required. 5. Replace the control unit (PCB). |
| 253 | V | RAM test error | 1. Restart the appliance to see if the problem re-occurs. 2. Check the electrical connections on the board (check for loose wires etc.). 3. Check the code plug is not damaged. 4. Replace the code plug if required. 5. Replace the control unit (PCB). |
| 254 | V | Eeprom test error | 1. Restart the appliance to see if the problem re-occurs. 2. Check the electrical connections on the board (check for loose wires etc.). 3. Check the code plug is not damaged. 4. Replace the code plug if required. 5. Replace the control unit (PCB). |
| 258 | V | Internal watchdog error | 1. Restart the appliance to see if the problem re-occurs. 2. Check the electrical connections on the board (check for loose wires etc.). 3. Check the code plug is not damaged. 4. Replace the code plug if required. 5. Replace the control unit (PCB). |
| 259 | V | AD reference error | 1. Restart the appliance to see if the problem re-occurs. 2. Check the electrical connections on the board (check for loose wires etc.). 3. Check the code plug is not damaged. 4. Replace the code plug if required. 5. Replace the control unit (PCB). |
| 262 | V | Internal OS error | 1. Restart the appliance to see if the problem re-occurs. 2. Check the electrical connections on board (check for loose wires etc.). 3. Check the code plug is not damaged. 4. Replace the code plug if required. 5. Replace the control unit (PCB). |
| 263 | V | Program sequence error | 1. Restart the appliance to see if the problem re-occurs. 2. Check the electrical connections on the board (check for loose wires etc.). 3. Check the code plug is not damaged. 4. Replace the code plug if required. 5. Replace the control unit (PCB). |
| 265 | B | Heat demand lower than energy supplied | Not applicable, operating message, is not a fault. |
| 268 | O | Relay test was activated | Not applicable, status message. |
| 269 | V | Flame monitoring | 1. Restart the appliance to see if the problem re-occurs. 2. Check the electrical connections on the board (check for loose wires etc.). 3. Replace the control unit (PCB). |
| 273 | B | Operation of burner and fan interrupted | Not applicable, status message. |
| 281 | B | Pump pressure increase too low | 1. Check the flow pressure in system. 2. Check the system for circulation issues (air locks, blockage, restriction). 3. Check that the tacho cable plug for the circulation pump is fitted correctly. 4. Check the tacho cable for continuity and replace the tacho cable if required. 5. Replace the pump. |
| 283 | O | Burner starting | Operating message, is not a fault. |
| 284 | O | Opening air/gas ratio control valve/oil solenoid valves | Operating message, is not a fault. |
| 305 | O | Boiler in hot water anti-cycle mode | Anti-fast cycle mode, domestic hot water keep warm function. 1. Diverter valve is held in the hot water position for a period of time. 2. Check for false demands on the cold water inlet. |
| 306 | V | Flame signal after closing the fuel supply | Tip: Ensure the working pressure returns immediately to the standing pressure when the gas valve closes. 1. Check the gas supply to the property and the inlet on the gas valve (check drop on inlet). 2. Check the gas valve is not passing and replace if required. 3. Replace the PCB. |
| 352 | Test blocking error | Flue gas pressure module (FOM) is defective or interrupted. | |
| 353 | Test non-volatile lockout | Device may not start temporarily, never been off for 20 min for 24 h. | |
| 354 | Test volatile lockout | Overpressure setting is detected. | |
| 357 | O | Ventilation program | Operating message, is not a fault: Venting program has been activated. |
| 358 | O | Anti-seizing functn. active | Operating message, is not a fault: blocking protection for the heating pump and the 3-way valve is active. |
| 360 | V | Incomparable code plug | 1. Wrong code plug is inserted. 2. Check the code plug is not damaged. 3. Replace the code plug if required. |
| 362 | V | Boiler identification module or boiler electronics faulty | 1. Wrong code plug is inserted. 2. Check the code plug is not damaged. 3. Replace the code plug if required. |
| 363 | V | Ionisation current did not drop during ionisation test | 1. Check and replace the ionisation cable. 2. Check and replace the electrodes if required. 3. Check and replace the control unit and/or burner control unit. |
| 815 | W | Low loss header temp. sensor faulty | Tip: Check menu has not been accidently switched on. Moisture on the connectors – PCB fault. |
| 1010 | O | No BUS communication | 1. Check the HMI plug on far right of the PCB (low voltage connection). 2. If using the Key: Check the Key connections (black, white, red, green) are plugged in to the correct position on the PCB. (Next to orange BUS connection leaving one space.) Check the pins on the plug. 3. Check the bridging links are in LR & 230 V out. 4. Replace the board. 5. Occasionally the Key connection (green flap) can cause this. 6. Check the 230 V external wiring does not run alongside the BUS connections. |
| 1013 | Max. combustion point reached | 1. Check the maintenance menu. 2. Reset the maintenance code via the reset menu. | |
| 1017 | W | System pressure too low | 1. Top up water and vent the system. 2. Check the voltage to the pressure sensor and the signal back from the pressure sensor. 3. Replace the pressure sensor. |
| 1018 | Maintenance interval expired | 1. Check the maintenance date set in the menu. 2. Reset the maintenance code via the reset menu. | |
| 1019 | Incorrect pump type detected | 1. Pump communication failure or wrong pump is fitted (non-ErP). 2. Check the pump communication wire is connected and has continuity. 3. Replace the pump for correct modulating pump. | |
| 1021 | B | Cylinder charging or hot water temperature sensor faulty | 1. Check the domestic hot water temperature sensor connected and the plug connected to temperature sensor. 2. Check the resistance of the temperature sensor and replace if required. 3. Check the continuity of harness and replace if required. |
| 1023 | Maximum run time including standby time reached | 1. Check the maintenance menu. 2. Reset the maintenance code via the reset menu. | |
| 1025 | Return temp. sensor is faulty | Not fitted on the boiler. | |
| 1037 | W | Outside temp. sensor faulty - heating back- up operation active | Tip: Check the weather compensation is applicable and the menu has not been accidently switched on in the menu. 1. Check the positioning of the outside weather sensor. 2. Check the weather sensor connections on the control board. 3. Check the resistance of the sensor and the continuity down the cable and replace if required. |
| 1065 | B | System pressure sensor faulty or not connected | 1. Check the water pressure sensor plug is connected. 2. Plug the connection plug on the water pressure sensor correctly. 3. Check the continuity of harness and replace if required. 4. Check the voltage to the pressure sensor and the return voltage to the pressure sensor. 5. Replace the pressure sensor. |
| 1068 | W | Outside temp. sensor or lambda probe faulty | 1. Check the outdoor sensor plug is connected. 2. Check the resistance of the sensor and replace if required. 3. Check the continuity of harness and replace if required. 4. Replace the outdoor sensor. |
| 1070 | The next maintenance is due on | Advanced service reminder warning. 1. Check the maintenance menu. 2. Reset the maintenance code via the reset menu. | |
| 1071 | The next maintenance is now due please call your installer. phone | 1. Check the maintenance menu. 2. Reset the maintenance code via the reset menu. | |
| 1072 | Maintenance is overdue please call your installer. phone | 1. Check the maintenance menu. 2. Reset the maintenance code via the reset menu. | |
| 1073 | W | Short circuit of the flow temperature sensor | 1. Check the flow temperature sensor plug is connected. 2. Check the resistance of the flow temperature sensor and replace if required. 3. Check the continuity of harness and replace if required. 4. Replace the flow temperature sensor. |
| 1074 | W | No signal from flow temperature sensor | 1. Check the flow temperature sensor plug is connected. 2. Check the resistance of the flow temperature sensor and replace if required. 3. Check the continuity of harness and replace if required. 4. Replace the flow temperature sensor. 5. Replace the PCB. |
| 1075 | W | Short-circuit heat exchanger temperature sensor | 1. Check the temperature sensor plug is connected. 2. Check the resistance of sensor and replace if required. 3. Check the continuity of harness and replace if required. 4. Replace the temperature sensor. 5. Replace the PCB. |
| 1076 | W | No signal from heat exchanger temperature sensor | 1. Replace the temperature sensor plug is connected. 2. Check the resistance of sensor and replace if required. 3. Check the continuity of harness and replace if required. 4. Replace the temperature sensor. 5. Replace the PCB. |
| 2085 | V | Internal fault | 1. Reset the appliance. 2. Switch off the appliance for 30 s then turn back on. 3. Check the incoming mains voltage. 4. Check the polarity. 5. Replace the PCB. |
| 2908 | V | System fault boiler electronics/basic controller | 1. Restart the appliance to see if the problem re-occurs. 2. If the fault remains after resetting: the burner controller (PCB) is defective and must be replaced. |
| 2910 | V | Fault in flue system | 1. Check the flue for obstructions and remove any found. 2. Check the flue integrity test. 3. Check for water in the sump and check the siphon operation. |
| 2914 | There is no communication between the appliance controller and burner module | 1. Restart the appliance to see if the problem re-occurs. 2. If the fault remains after resetting: the burner controller (PCB) is defective. | |
| 2915 | V | The fan keeps running after the post purge | 1. Reset the appliance. 2. Create a heat demand does the boiler fire up. 3. Check the voltage to the fan and the continuity of the fan harness. 4. Check the power modulation on the fan. 5. PCB is may be defective. |
| 2916 | V | Gas valve was detected to be open during post purge | 1. Carry out a localised tightness test on the gas valve and replace if required. 2. Check the voltage to gas valve. 3. The gas valve or the PCB may have a fault. |
| 2920 | V | Fault in flame monitoring | Possible PCB fault, no checks available. |
| 2923 | V | Unexpected feedback from the modulating/ current controlled gas valve | Possible PCB fault, no checks available. |
| 2924 | V | No feedback from the gas valve | 1. Check the voltage to the gas valve. 2. Check the resistance of the gas valve coils. 3. Check the continuity of harness and replace if required. 4. The gas valve or the PCB may have a fault. |
| 2925 | V | Too low feedback from the modulating gas valve | 1. Check the voltage to the gas valve. 2. Check the resistance of the gas valve coils. 3. Check the continuity of harness and replace if required. 4. The gas valve or the PCB may have a fault. |
| 2926 | V | Too high feedback from the modulating/ current controlled gas valve | 1. Check the voltage to the gas valve. 2. Check the resistance of the gas valve coils. 3. Check the continuity of harness and replace if required. 4. The gas valve or the PCB may have a fault. |
| 2927 | B | Flame failed during burner operation | 1. Check the gas supply to the property and the inlet on the gas valve (check drop on inlet) and replace if required. 2. Check the flame sense probe and the earth to the heat exchanger. 3. Check the voltage to the gas valve and the continuity of harness and replace if required. 4. Check the condition of the bearing plate. 5. Check the flame sense plug is connected and the continuity of harness and replace if required. 6. Check the fan pressure. 7. Check the siphon trap and the discharge route. 8. Check the flue integrity test. |
| 2928 | Internal error | 1. Restart the appliance to see if the problem re-occurs. 2. If the fault remains after resetting: the burner controller (PCB) is defective. | |
| 2931 | Illegal instruction executed by microcontroller | 1. Restart the appliance to see if the problem re-occurs. 2. If the fault remains after resetting: the burner controller (PCB) is defective. | |
| 2940 | V | Low voltage | 1. Restart the appliance to see if the problem re-occurs. 2. If the fault remains after resetting: the burner controller (PCB) is defective. |
| 2946 | V | Incorrect code plug detected | 1. Check the code plug and the part number. 2. Check the code plug connections for damage. 3. Replace the code plug. |
| 2948 | B | No flame signal with low output | The burner starts automatically after purging. It may cause strong winds. 1. If the fault occurs repeatedly: check the settings of the CO2 values. 2. Check the flue integrity. 3. Check the flue terminal. |
| 2949 | B | No flame signal with high output | It may cause strong winds or flue gas recirculation. The burner starts automatically after purging. 1. Check the flue integrity. 2. Check the flue terminal position. 3. Check the CO2 settings and adjust. 4. Check the burner and the heat exchanger gaskets and the inner flue gaskets. 5. Check the gas pressure during burning at full load (working pressure, dropping low). |
| 2950 | B | No flame signal following starting procedure | 1. Check the CO2 settings and adjust. 2. Check the burner and the heat exchanger gaskets. 3. Check the gas pressure during burning at full load. 4. Burner restarts automatically after purging. |
| 2951 | V | Loss of flame too many times | Note: Combustion case off can case this fault. 1. Refer to blocking errors(s) that lead to this locking error. Check the fault history on the appliance. 2. Possibly the purging of the gas pipe is incomplete. 3. It could also indicate a wide variety of issues such as pipework undersized or gas pressure dropping off, incorrectly routed condens drains, incorrectly sited flues, incorrectly wired etc. |
| 2952 | V | Internal fault when testing ionisation signal | 1. Restart the appliance to see if the problem re-occurs. 2. If the fault remains after resetting: the burner controller (PCB) is defective. |
| 2955 | B | Boiler does not support the parameters set for the hydraulic configuration | Verify that the following settings are correct. This can only be reset by powering off the appliance. 1. Low loss header setting = OFF 2. Internal DHW hydraulic = 1/ON 3. Heat circuit 1 hydraulic = 1/ON 4. CH hydraulic = 1/ON |
| 2956 | O | Hydraulic configuration at the boiler activated | Verify that the following settings are correct. This can only be reset by powering off the appliance. 1. Low loss header setting = OFF 2. Internal DHW hydraulic = 1/ON 3. Heat circuit 1 hydraulic = 1/ON 4. CH hydraulic = 1/ON |
| 2957 | V | Internal burner control error | 1. Restart the appliance to see if the problem re-occurs. 2. If the fault remains after resetting: the burner controller (PCB) is defective and must be replaced. |
| 2961 | V | No fan signal available | 1. Check the mains voltage to the fan. 2. Check the fan harness for continuity and replace if required. 3. Check the pulse width modulation (PWM). 4. Replace the fan. 5. Replace the PCB. |
| 2962 | V | Fan not running | 1. Check the mains voltage to the fan. 2. Check the fan harness for continuity and replace if required. 3. Check the pulse width modulation (PWM). 4. Replace the fan. 5. Replace the PCB. |
| 2963 | B | Signal from flow and heat exchanger temperature sensor outside the permissible range | 1. Check the flow through the appliance and the system is filled. 2. Check for air locks in the system and purge if required. 3. Check the heat exchanger sensor (primary thermistor) and the plug connected to temperature sensor. 4. Check the resistant of the temperature sensor and replace if required. 5. Check the continuity of harness and replace if required. |
| 2964 | B | Flow rate in heat exchanger too low | 1. Supply sensor is not on the supply pipe. 2. Supply sensor does not make proper contact to the supply pipe. 3. Check the sensor and the flow sensor are making contact with the pipework. 4. Check the system filled with water. 5. No water flow, because the CH system is closed. 6. No water flow, because the pump is not operating correctly. |
| 2965 | B | Flow temperature too high | 1. Check the flow through the appliance and the system is filled. 2. Check for the air locks in the system and purge if required. 3. Check the isolation valves. |
| 2966 | B | Flow temperature rise in heat exchanger too rapid | 1. Check the flow through the appliance and the system is filled. 2. Check for the air locks in the system and purge if required. 3. Check the isolation valves. 4. Check the pump is operating freely and check the voltage to the pump. |
| 2967 | B | Flow/heat exchanger temperature sensor differential too great | 1. Check the flow through the appliance and the system is filled. 2. Check for air locks in the system and purge if required. 3. Check the isolation valves. 4. Check the pump is operating freely and check the voltage to the pump. 5. Check the heat exchanger sensor and the flow sensor are making contact with the pipework. 6. Check the heat exchanger sensor and the resistance of the temperature sensor and replace if required. 7. Check the continuity of harness and replace if required. |
| 2968 | O | Refilling system pressure | The auto filling function is active. The filling valve opens in order to feed fresh water to the heating system automatically. |
| 2969 | Maximum number of refills reached | The maximum number of refills has been reached. | |
| 2970 | B | Pressure drop in heating system too rapid | Too many unexpected pressure drops within a short time period. 1. Cause code can appear if system is pressurised and the intelligent filling loop activated and then the system vented. 2. Switch off the intelligent fill in the system menu, re-pressurise manually and vent the system. 3. Ensure the correct pressure. If cause code does not clear power off appliance. |
| 2971 | B | System pressure too low | Compare to internal pressure dial max. 0.5 bar pressure differential between them. Top up water until the pre-set pressure reached. Intelligent filling loop 1. Switch off the intelligent fill in the system menu, re-pressurise manually and vent the system. 2. Ensure the correct pressure then factory rest appliance. If cause code does not clear power off appliance. Other filling loop Vent the heating system and top up water until the pre-set pressure reached. Pressure sensor 1. Check the continuity down harness for the pressure sensor and replace if required. 2. Check the voltage at the pressure sensor and replace if required. |
| 2972 | Mains voltage too low | Check the mains voltage on the appliance (L and N). | |
| 3071 | Comfort + II RF | 1. Check the configuration (address setting). The selected setting requires a remote control. 2. Check the EMS connection cable for the remote control for damage. The BUS voltage on the remote control must be between 12 and 15 V DC. 3. The remote control is defective. |
Faults that are not Displayed
| Appliance faults | Remedy |
| Combustion noises too loud; rumbling noises | ▶ Check the gas type. ▶ Check the gas supply pressure. ▶ Check the flue system; clean or repair if required. ▶ Check the gas/air ratio. ▶ Check the air/gas ratio control valve; replace if required. |
| Flow noises | ▶ Set the pump rate or pump characteristic map correctly and match to the maximum output. |
| Heat-up takes too long. | ▶ Set the pump rate or pump characteristic map correctly and match to the maximum output. |
| Flue gas values incorrect; CO content too high. | ▶ Check the gas type. ▶ Check the gas supply pressure. ▶ Check the flue system; clean or repair if required. ▶ Check the gas/air ratio. ▶ Check the air/gas ratio control valve; replace if required. |
| Violent ignition, poor ignition. | ▶ Check the ignition transformer with service function t01 for misfiring, replace if required. ▶ Check the gas type. ▶ Check the gas supply pressure. ▶ Check the power supply. ▶ Check the electrodes with cable; replace if required. ▶ Check the flue system; clean or repair if required. ▶ Check the gas/air ratio. ▶ For natural gas: check the external gas flow monitor, replace if required. ▶ Check the burner, replace if required. ▶ Check the air/gas ratio control valve; replace if required. |
| Condensate in air box | ▶ Check the non-return valve in the air-gas manifold, replace if required. |
| Combi boilers: hot water outlet temperature is not reached. | ▶ Check the turbine, replace if required. ▶ Check the gas/air ratio. |
| Combi boilers: DHW volume is not reached. | ▶ Check the plate heat exchanger. |
| No function, the display remains dark. | ▶ Check the electrical wiring for damage. ▶ Replace defective cables. ▶ Check the fuse, replace if required. |
Worcester Bosch Greenstar CDi Compact Gas Boiler Fault Codes
| Fault codes Should a fault develop with this boiler (or the system), the boiler will enter a locking or blocking condition, and fault code information will be generated as described in this section. | ||||||
| Locking error | The boiler display will flash a warning triangle and fault code. At the same time, a (static) cause code will also be displayed. Manual intervention is required following clearance of the fault: ▶ Press the reset button on the boiler fascia | |||||
| Blocking error | The boiler will stop operating with no-fault data displayed. The cause code, in the info menu, is accessed by pressing the spanner/return button. The condition will clear automatically when the associated fault clears e.g. waiting for an area to cool. In some cases a blocking error has a defined time duration prior to changing to a locking condition. | |||||
| Fault code | Alphanumeric number indicating the fault group | |||||
| Cause code | Three-digit number. During a blocking error (or normal operating status) it is not displayed, but accessed in the info menu via the spanner/return button. During a locking error, the cause code flashes on the display. | |||||
Worcester Bosch Greenstar CDi Compact Gas Boiler Locking Errors
Worcester Bosch Greenstar CDi Compact Gas Boiler Blocking Errors
Locking Errors
| Fault codes | Cause codes | Description | Reset type | Possible cause | |
|---|---|---|---|---|---|
| 9U | 233 | HCM (Heat Control Module) | Reset button | Problem with the code plug | |
| b7 | 257 | Internal error | Replace control board. | ||
| C6 | 215 | Fan problem | Reset button | Fan running too fast | |
| 216 | Fan problem | Reset button | Fan running too slow | ||
| C7 | 214 | Fan problem | Reset button | Fan not running | |
| 217 | No airflow after a defined period of time | Reset button | Fan not running or airflow blocked | ||
| D1 | 240 | Return sensor error | Reset button | Sensor wet or damaged (the boiler will block for 300 secs before this condition). | |
| 241 | Return sensor error | Reset button | Sensor disconnected or damaged (the boiler will block for 300 secs before this condition). | ||
| 286 | Return temperature too high | Reset button | Boiler overheat | ||
| E2 | 222 | Flow sensor short circuit | Reset button | Flow sensor shorted or damaged. | |
| 223 | Flow sensor open circuit | Reset button | Flow sensor disconnected or damaged. | ||
| E5 | 218 | Flow temperature too high | Reset button | Primary flow sensor overheated | |
| 332 | Primary flow sensor has exceeded 110°C | Reset button | Primary flow sensor overheated | ||
| E9 | 219 | Safety sensor temperature too high | Reset button | The main heat exchanger has overheated. Maximum temperature 105C° | |
| 220 | Safety sensor short circuit | Reset button | Maximum temperature sensor on the main heat exchanger has failed. | ||
| 221 | Safety sensor open circuit | Reset button | Maximum temperature sensor on the main heat exchanger has not been recognised. | ||
| 224 | Max temperature thermostat activated | Reset button | Flue gas thermostat overheat | ||
| EA | 227 | No flame detected after ignition | Reset button | Failure of four ignition attempts. The boiler waits 30 seconds before another attempt is made. | |
| 229 | Loss of flame signal during operation | Reset button | An established flame has been extinguished. This could be caused by: • moisture in the sump, due to a blocked sump/condensate trap. • a strong wind into the flue. | ||
| 234 | Gas valve error | Reset button | Gas valve coil disconnected | ||
| 261 | Ignition timing error | Reset button | Flame not established during the first 4 seconds ignition period. | ||
| F0 | 237 - 239 242 - 256 258 259 262 263 267 272 279 290 | Internal error | Call Worcester, Bosch Group Technical helpline 0330 123 3366 | ||
| 278 | Sensor test failed | Reset button | On power up all safety sensors are checked. Check has failed. | ||
| 280 | Recycle time error | Reset button | After the burner has stopped, the recycle mode purges gas from the heat exchanger before attempting to burn again. The software has 3.1 seconds to intervene before the boiler goes into this fault condition. | ||
| 338 | Too many short burner starts without confirmation | Reset button | There is an error where the pump is not detecting water. | ||
| F7 | 228 | Flame error | Reset button | False flame. Flame detected before burner start. | |
| 328 | Internal error | Replace control board | |||
| FA | 306 | False flame error | Reset button | Flame detected after burner stop | |
| FD | 231 | Mains power error | Reset button | Electrical power interruption. | |
| FA | 364 | Gas valve EV2 leak test failed | Reset button | Gas valve leak. | |
| Fb | 365 | Gas valve EV1 leak test failed | Reset button | Gas valve leak. |
Blocking Errors
| Fault code | Cause code | Description | Possible cause |
|---|---|---|---|
| A1 | 281 | Pump stuck or running in air | Little or no water in the system. |
| C1 | 264 | Airflow stopped during operation | Fan has stopped. |
| C4 | 273 | Airflow present during last 24 hours | Fan has been running continuously during the past 24 hours. |
| D1 | 240 | Return sensor short circuit | |
| 241 | Return sensor disconnected | ||
| D4 | 271 | Temperature difference between flow and safety sensors exceeds limit | The temperature of the primary flow and the safety sensor on the WB7 should bewithin 15°C of each other. |
| E9 | 224 | MAX thermostat activated | Flue gas thermostat overheat. |
| 276 | Flow temperature exceeds 95°C | Primary overheat - boiler waits for temperature to reduce; if not it becomes a Locking error. | |
| 277 | Safety temperature exceeds 95°C | Main heat exchanger safety sensor overheat - boiler will wait for the temperature to reduce; if not it becomes a Locking error 219. | |
| 285 | Return temperature exceeds 95°C | The boiler will stop the burn and wait to see if it cools down. If after 2 seconds there is an increase in temperature the boiler will go to Locking error 286. | |
| EA | 227 | No ionisation detected after ignition | No flame is detected. The boiler will block during 4 attempts before going to Locking fault. |
| EF | 349 | Central heating, boil detect. Large delta T despite minimum burrner. | The boiler is operating at minimum burner load and there is a greater than 18°C Flow & Return temperature difference. |
| No code | 212 | Safety or flow temperature rises too fast | Air lock or reduced water content. |
| 213 | Temperature difference between supply and return exceeding limit | Air lock or reduced water content. | |
| 260 | No temperature rise after burner starts | Sensor disconnected or no water content. | |
| 380 | Inlet DHW temperature higher than the DHW outlet temperature. | The output is blocked until the inlet temperature drops below the output temperature. |
Worcester Bosch Greenstar CDi Highflow Gas Boiler Fault Codes
Condensate Pump Operating Lights
Fault Codes
| Display code: | Fault description | Check, repair/replace as necessary |
|---|---|---|
| A1 | Pump dry run detection or Pump is running in air | Check the system pressure, refill if necessary |
| A5 | Tank NTC defect | Check tank NTC sensor and leads, measure resistance across NTC (33.5k - 500 ) |
| A7 | DHW NTC defect | Check DHW NTC sensor and leads, measure resistance across NTC (33.5k - 500 ) |
| A8 | EMS communication error | Check electrical connections of EMS controls (if fitted), connections on the control board, replace control board. |
| b1 | Code plug not detected | Insert code plug correctly, test and replace as necessary. |
| b2, b3, b4, b5,b6 | Data error | Replace control board. |
| b7 | Burner control error | Replace control board. |
| C6 | Fan defect | Check fan, lead, and connector, replace as necessary. |
| d3 | External temp limiter | Check plug connector ST8, link missing/damaged between 8 & 9 on ST8. |
| d5 | Condensate pump failure | See condensate pump table. |
| d6 | Internal heat bank overflow | Check system pressure, tank overheat thermostat and leads, and pump operation |
| EA | Flame not detected | Check gas is present and working gas pressure, ignition electrodes and harness, flame sense electrode and harness, and operation of gas valve. Replace as necessary. |
| E2 | Primary NTC defect | Check primary NTC sensor and leads, resistance across NTC should be between 36k to 1k |
| E9 | OH stat tripped | Check system pressure, over heat thermostat, and pump operation. Check fuse (T1.6A slow blow), replace as necessary. |
| F0 | Internal error | Check all electrical connections, replace control board as necessary. |
| F1 | ROM error check | Check all electrical connections, replace control board as necessary. |
| F7 | Flame detected after appliance shut off | Check flame sense electrode and harness, and control board for signs of water damage. Replace as necessary |
| FA | Flame detected after gas shut off | Check flame sense electrode and harness, and control board for signs of water damage. Check gas valve operation. Replace as necessary |
| Fd | Reset button pressed | Press reset button again |
Condensate Pump Operating Lights
| Operating lamps | Cause | Solution | ||
| Green | Red | |||
| Off | Off | Mains supply not connected Power failure | Connect mains supply Check mains and fuse/circuit breaker | |
| Flashing | Flashing | Dry-run (possible air in pump) | Pump restarts automatically after one minute | |
| On | Flashing | Pump blocked | Visually inspect the pump inlet and tank. Remove or rinse out any dirt or foreign bodies | |
| On | On | Level exceeds alarm level | Discharge hose or non-return valve blocked Possible kink in discharge hose (clean or remove kink if applicable) | |
| Off | Flashing | Pump blocked and alarm level exceeded | Visually inspect the pump inlet and tank. Remove or rinse out any dirt or foreign bodies | |
Worcester Bosch Greenstar CDi Highflow Gas Boiler Fault Codes
Worcester Bosch Greenstar CDi Highflow Gas Boiler Fault Codes
Worcester Bosch Greenstar CDi Highflow Gas Boiler Condensate Pump Operating Lights
Fault Codes
| Display code: | Fault description | Check, repair/replace as necessary |
|---|---|---|
| A1 | Pump dry run detection or Pump is running in air | Check the system pressure, refill if necessary |
| A5 | Tank NTC defect | Check tank NTC sensor and leads, measure resistance across NTC (33.5k - 500 ) |
| A7 | DHW NTC defect | Check DHW NTC sensor and leads, measure resistance across NTC (33.5k - 500 ) |
| A8 | EMS communication error | Check electrical connections of EMS controls (if fitted), connections on the control board, replace control board. |
| b1 | Code plug not detected | Insert code plug correctly, test and replace as necessary. |
| b2, b3, b4, b5,b6 | Data error | Replace control board. |
| b7 | Burner control error | Replace control board. |
| C6 | Fan defect | Check fan, lead, and connector, replace as necessary. |
| d3 | External temp limiter | Check plug connector ST8, link missing/damaged between 8 & 9 on ST8. |
| d5 | Condensate pump failure | See condensate pump table. |
| d6 | Internal heat bank overflow | Check system pressure, tank overheat thermostat and leads, and pump operation |
| EA | Flame not detected | Check gas is present and working gas pressure, ignition electrodes and harness, flame sense electrode and harness, and operation of gas valve. Replace as necessary. |
| E2 | Primary NTC defect | Check primary NTC sensor and leads, resistance across NTC should be between 36k to 1k |
| E9 | OH stat tripped | Check system pressure, over heat thermostat, and pump operation. Check fuse (T1.6A slow blow), replace as necessary. |
| F0 | Internal error | Check all electrical connections, replace control board as necessary. |
| F1 | ROM error check | Check all electrical connections, replace control board as necessary. |
| F7 | Flame detected after appliance shut off | Check flame sense electrode and harness, and control board for signs of water damage. Replace as necessary |
| FA | Flame detected after gas shut off | Check flame sense electrode and harness, and control board for signs of water damage. Check gas valve operation. Replace as necessary |
| Fd | Reset button pressed | Press reset button again |
Condensate Pump Operating Lights
| Operating lamps | Cause | Solution | ||
| Green | Red | |||
| Off | Off | Mains supply not connected Power failure | Connect mains supply Check mains and fuse/circuit breaker | |
| Flashing | Flashing | Dry-run (possible air in pump) | Pump restarts automatically after one minute | |
| On | Flashing | Pump blocked | Visually inspect the pump inlet and tank. Remove or rinse out any dirt or foreign bodies | |
| On | On | Level exceeds alarm level | Discharge hose or non-return valve blocked Possible kink in discharge hose (clean or remove kink if applicable) | |
| Off | Flashing | Pump blocked and alarm level exceeded | Visually inspect the pump inlet and tank. Remove or rinse out any dirt or foreign bodies | |
Worcester Bosch Greenstar 8000 Style Gas Boiler Fault Codes
Worcester Bosch Greenstar 8000 Style Gas Boiler Fault Codes
Worcester Bosch Greenstar 8000 Style Gas Boiler Faults that are not displayed
Fault Codes
| Fault code | Fault category | Description | Remedy |
|---|---|---|---|
| 200 | O | Boiler in heating mode | – |
| 201 | O | Boiler in hot water mode | – |
| 202 | O | Boiler in anti-cycle mode | – |
| 203 | O | Boiler in standby, no heat energy demand | – |
| 204 | O | Current prim. water temp. higher than set val. | – |
| 208 | O | Chimney sweep demand | – |
| 224 | V | Safety temp. limiter has tripped | 1. Open the closed valve in the heating circuit. 2. Top up water until the preset pressure is reached. 3. Connect the plug correctly to the safety temperature limiter. 4. Replace the safety temperature limiter. |
| 227 | V | No flame signal after ignition | 1. Open the gas isolator. 2. Change the gas installation. 3. Replace the control unit/burner control unit. 4. Replace the ignition electrode. 5. Replace the monitoring electrode. 6. Replace the ignition cable. 7. Replace the ionisation cable. 8. Replace the air/gas ratio control valve. 9. Correct the burner setting. |
| 228 | V | Flame signal without flame present | 1. Replace the air/gas ratio control valve. 2. Replace the ionisation cable. 3. Replace the control unit/burner control unit. |
| 305 | O | Boiler in hot water anti-cycle mode | – |
| 306 | V | Flame signal after closing the fuel supply | 1. Replace the air/gas ratio control valve. 2. Replace the ionisation cable. 3. Replace the control unit/burner control unit. |
| 815 | B | Low loss header temp. sensor faulty | 1. Check the sensor port. 2. Check the differential sensor for incorrect installation position or breakage. |
| 1017 | W | Water pressure too low | 1. Top up water and vent the system. 2. Replace the pressure sensor. |
| 1021 | B | Hot water temperature sensor is defective | 1. Connect the plug to the hot water temperature sensor correctly. 2. Mount the hot water temperature sensor correctly. 3. Replace the hot water temperature sensor. 4. Replace the connecting lead to the hot water temperature sensor. |
| 1037 | W | Outside temperature sensor defective | Check the connecting lead. |
| 1065 | B | Pressure sensor defective or not connected | 1. Connect the plug to the pressure sensor correctly. 2. Replace the connecting lead to the pressure sensor. 3. Replace the pressure sensor. 4. Replace the control unit. |
| 1068 | W | Outside temperature sensor defective | Check the connecting lead. |
| 1073 | W | Short circuit of the flow temperature sensor | 1. Replace the temperature sensor. 2. Replace the connecting lead to the temperature sensor. 3. Replace the control unit. |
| 1074 | W | No signal from the flow temperature sensor available | 1. Connect the plug to the flow temperature sensor correctly. 2. Replace the flow temperature sensor. 3. Replace the connecting lead to the flow temperature sensor. 4. Replace the control unit. |
| 1075 | W | Short circuit of the temperature sensor at the heating block | 1. Replace the temperature sensor. 2. Replace the connecting lead to the temperature sensor. 3. Replace the control appliance. |
| 1076 | W | No signal from the temperature sensor at the heating block available | 1. Replace the temperature sensor. 2. Replace the connecting lead to the temperature sensor. 3. Replace the control unit. |
| 2920 | V | Fault in flame monitoring | – |
| 2927 | B | Flame failed during burner operation | 1. Open the main shut-off valve. 2. Open the appliance shut-off valve. 3. Shut down the appliance and check the gas line. 4. Signal evaluation on printed circuit board defective. 5. Replace the ionisation electrode. 6. Establish protective conductor connection (PE) in the control unit. 7. Replace the ignition cable. 8. Replace the connecting lead to the ionisation electrode. 9. Replace the air/gas ratio control valve. 10.Set the burner correctly. 11.Set the burner at minimum rated load. 12.Check the integrity flue system. 13.The interconnected room air supply is too small or the size of the ventilation opening is too small. 14.Clean the heating block on the flue gas side. 15.Replace the control unit/burner control unit. |
| 2946 | V | Incorrect code plug detected | Replace the code plug. |
| 2948 | B | No flame signal with low output | The burner starts automatically after cleaning. 1. If the fault occurs repeatedly: check the settings of the CO2 values. |
| 2950 | B | No flame signal following starting procedure | The burner starts automatically after cleaning. 1. Set the correct gas/air ratio correctly. |
| 2963 | B | Signal from flow and heat exchanger temperature sensor outside the permissible range | Connect the connecting lead correctly. |
| 2964 | B | Flow rate in heat exchanger too low | – |
| 2965 | B | Flow temperature too high | – |
| 2966 | B | Flow temperature rise in heat exchanger too rapid | – |
| 2967 | B | Flow/ heate exchanger temperature sensor differential too great | – |
| 2970 | B | Pressure drop in heating system too rapid | – |
| 2971 | B | System pressure too low | 1. Vent the heating system. 2. Top up water until the preset pressure is reached. 3. Replace the cable to the pressure sensor. 4. Replace the pressure sensor. |
Faults that are not Displayed
| Appliance faults | Remedy |
| Combustion noises too loud; rumbling noises | ▶ Check the gas type. ▶ Check the gas supply pressure. ▶ Check the flue system; clean or repair if required. ▶ Check the gas/air ratio. ▶ Check the air/gas ratio control valve; replace if required. |
| Flow noises | ▶ Set the pump rate or pump characteristic map correctly and match to the maximum output. |
| Heat-up takes too long. | ▶ Set the pump rate or pump characteristic map correctly and match to the maximum output. |
| Flue gas values incorrect; CO content too high. | ▶ Check the gas type. ▶ Check the gas supply pressure. ▶ Check the flue system; clean or repair if required. ▶ Check the gas/air ratio. ▶ Check the air/gas ratio control valve; replace if required. |
| Violent ignition, poor ignition. | ▶ Check the ignition transformer with service function t01 for misfiring, replace if required. ▶ Check the gas type. ▶ Check the gas supply pressure. ▶ Check the power supply. ▶ Check the electrodes with cable; replace if required. ▶ Check the flue system; clean or repair if required. ▶ Check the gas/air ratio. ▶ For natural gas: check the external gas flow monitor, replace if required. ▶ Check the burner, replace if required. ▶ Check the air/gas ratio control valve; replace if required. |
| Condensate in air box | ▶ Check the non-return valve in the air-gas manifold, replace if required. |
| Combi boilers: hot water outlet temperature is not reached. | ▶ Check the turbine, replace if required. ▶ Check the gas/air ratio. |
| Combi boilers: DHW volume is not reached. | ▶ Check the plate heat exchanger. |
| No function, the display remains dark. | ▶ Check the electrical wiring for damage. ▶ Replace defective cables. ▶ Check the fuse, replace if required. |
Worcester Bosch Greenstar Heatslave II Oil Boiler Fault Codes
| Cause code | Fault code | Description | Reset type | Blocking | Locking | Possible cause/solution |
|---|---|---|---|---|---|---|
| 210 | E9 | Maximum temperature thermostat or air pressure switch activated | Reset | X | Flue gas or tank thermostat overheat. Reset the overheat thermostat or air pressure switch before resetting appliance. | |
| 212 | No code | Safety or flow temperature too high | X | Air lock or reduced water content. | ||
| 218 | E5 | Flow temperature too high | Reset | X | Primary sensor overheated, wait 30 minutes and try a reset. | |
| 219 | E9 | Safety temperature too high | Reset | X | The main heat exchanger has overheated. Maximum temperature 105°C, wait 30 minutes and try a reset. | |
| 220 | E9 | Safety sensor short circuit | Reset | X | Maximum temperature sensor on the main heat exchanger has failed. | |
| 221 | E9 | Safety sensor open circuit | Reset | X | Maximum temperature sensor on the main heat exchanger has not been recognised. | |
| 222 | E2 | Flow sensor short circuit | Reset | X | Flow sensor shorted or damaged, reconnect or replace as required. | |
| 223 | E2 | Flow sensor open circuit | Reset | X | Flow sensor disconnected or damaged, reconnect or replace as required. | |
| 233 | E2 | HCM (Heat Control Module) | Reset | X | HCM Code plug missing or defective. Refer to table 13, i22 and i23 to determine HCM number fitted | |
| 237 | F0 | Software relay error | Reset | X | Resistors between plug X4 pins 3 & 5 disconnected/>150k or water in the burner control box | |
| 238 | F0 | Software relay error | Reset | X | Resistors between plug X4 pins 3 & 5 disconnected/>150k or water in the burner control box | |
| 239 | F0 | Watchdog relay error | Reset | X | If the error persists, change the control board | |
| 259 | FO | A/D reference relay error | Reset | X | If the error persists, change the control board | |
| 263 | F0 | Appliance powered off with locking fault present | Reset | X | Locking fault still present when powered off/on, press the reset button to clear. | |
| 271 | D4 | Temperature difference between flow and safety sensors exceeds limit | X | The temperature of the primary flow and the safety sensor on the main heat exchanger should be within 15°C of each other. Check the flow sensor is seated properly on the flow pipe. | ||
| 276 | E9 | Flow temperature exceeds 95°C | X | Primary overheat - boiler waits for temperature to reduce, wait approximately 30 minutes and try a reset. | ||
| 277 | E9 | Safety temperature exceeds 95°C | X | Main heat exchanger safety sensor overheat - boiler waits for temperature to reduce, approximately 30 minutes. | ||
| 278 | F0 | Sensor test error | Reset | X | On power up, all safety sensors are checked. Check has failed. | |
| 279 | F0 | A/D converter error | Reset | X | If the error persists, change the control board | |
| 290 | F0 | A/D converter reference error | Reset | X | If the error persists, change the control board | |
| 332 | E5 | Primary flow has exceeded 105°C | Reset | X | Primary sensor overheated. | |
| 359 | No Code | DHW outlet or storage tank exceeds 90°C | X | Pump & burner are blocked until temperature drops to <89°C. wait approximately 30 minutes for temperature to drop. | ||
| 360 | 9A | Incorrect HCM for boiler variant | X | Replace with the correct HCM. Refer to table 13, i22 and i23 to determine HCM number fitted and select correct HCM number from list | ||
| 380 | No code | Inlet DCW temperature higher than DHW outlet temperature | X | The output is blocked until the inlet temperature drops below the output temperature, wait for approximately 30 minutes. | ||
| 808 | A7 | DHW sensor defective | Reset | X | Check and replace defect sensor as necessary | |
| 809 | A0 | Thermal store sensor defective | Reset | X | Check and replace defect sensor as necessary | |
| 855 | 9F | Burner lock out | Reset | X | Check the burner and fuel supply. Ensure the oil supply is free of contaminants. | |
| 856 | 9F | 5 burner lockouts repeated resets | Turn boiler off/on | X | After Five 855 burner lock outs in one demand period, cause code 856 is displayed. After boiler off/on cause code 263 will be displayed, press the reset button to clear this fault. another 5 burner lock resets can be attempted. | |
| H29 | Warning triangle and House symbol displayed on controller | Weather compensation activated but no weather sensor detected, refer to section 5.11 on page 32 for more information. | ||||
| H27 | Warning triangle symbol displayed on controller | DCW in sensor defect, (appliance operation not affected) |
Worcester Bosch Greenstar 24/28/30 Gas Combi Boiler Fault Codes
Worcester Bosch Greenstar 24/28/30 Gas Combi Boiler Fault Codes
Worcester Bosch Greenstar 8000 Style Gas Boiler Faults that are not displayed
Fault Codes
| Display | Remedy | |
|---|---|---|
| A7 | DHW temperature sensor faulty. | Check the temperature sensor and connecting lead for breaks or short circuits. |
| A8 | Communication fault. | Check BUS device connecting lead. |
| Ad | Cylinder temperature sensor not detected. | Check cylinder temperature sensor and connecting lead. |
| b1 | Code plug not detected. | Insert code plug correctly, test and replace if necessary. |
| b2 | Internal data error. | See servicing instructions for heating contractors. |
| b3 | ||
| C6 | Fan not running. | Check fan lead and connector, check fan, replace as necessary. |
| CC | Outside temperature sensor not detected. | Check outside temperature sensor and connecting lead for breaks. |
| d3 | External limiter has tripped. | Temperature limiter TB1 has tripped. Jumper across 8-9 or PR-P0 is missing. |
| d5 | External primary NTC on low loss header defect. | Check NTC and cable continuity. |
| E2 | Temperature sensor in CH flow faulty. | Check the temperature sensor and connecting lead. |
| E9 | Heat exchanger temperature limiter or flue gas temperature limiter has tripped. or Flue pipe is blocked. | Check system pressure, temperature limiter, pump operation, fuse on PCB bleed appliance. Check water-side of heat exchanger. On appliances with displacement bodies in heat exchanger, check whether displacement bodies are fitted. Check the flue (fresh air or exhaust gas) pipe blockage, check air pressure switch and air pressure switch pipe. Check heat exchanger high limit stat and flue high limit stat. |
| EA | Flame not detected. | Is gas tap open? Check gas supply pressure, mains power connection, electrodes and leads, flue pipe, gas-air ratio. On natural gas appliances, check external gas flow switch. |
| F0 | Internal fault. | Check electrical connectors and ignition leads, replace PCB if necessary. Check gas-air ratio. |
| F1 | Internal data error. | See servicing instructions for heating contractors. |
| F7 | A flame is detected although the appliance is switched off. | Check electrodes. Flue system OK? Check PCB for moisture. |
| FA | A flame is detected after the gas has been switched off. | Check gas valve. Clean condensate trap and check electrodes. Flue system OK? |
| Fd | Reset was pressed in error. | Press reset again. |
Faults that are not Displayed
| Appliance faults | Remedy | |
| Excessive combustion noise; rumbling noises | ▶ Insert coding plug correctly. Replace if required. ▶ Check gas type. ▶ Check gas supply pressure. Adjust if required. ▶ Check flue system. Clean or repair if required. ▶ Check gas-air ratio in the combustion air and flue gas. Replace gas valve if required. | |
| Flow noises | ▶ Set pump stages or pump parameters correctly and match to maximum output. | |
| Heat-up takes too long | ▶ Set pump stages or pump parameters correctly and match to maximum output. | |
| Flue gas readings incorrect; CO levels too high | ▶ Check gas type. ▶ Check gas supply pressure. Adjust if required. ▶ Check flue system. Clean or repair if required. ▶ Check gas-air ratio in flue gas. Replace gas valve if required. | |
| Ignition too strong, too weak | ▶ Check gas type. ▶ Check gas supply pressure. Adjust if required. ▶ Check power supply. ▶ Check electrodes and leads. Replace if required. ▶ Check flue system. Clean or repair if required. ▶ Check gas-air ratio. Replace gas valve if required. ▶ For natural gas: Check external gas flow limiter. Replace if required. ▶ Check burner. Replace if required. | |
| Set flow temperature exceeded | ▶ Switch OFF automatic cycle block, i.e. set the value to 0. ▶ Set the required cycle block, e.g. standard setting of 3 minutes. | |
| Condensate in air box | ▶ Insert diaphragm in the mixing facility as per installation instructions. Replace if required. | |
| DHW temperature is not reached | ▶ Insert coding plug correctly. Replace if required. ▶ Check whether voltage (230 V AC) is present across terminal 1 and terminal 3. Repair if required. ▶ Check flow meter. Replace if required. | |
| Control unit is flashing (i.e. all keys, all display segments, burner indicator etc. are flashing) | ▶ Replace fuse Si 3 (24 V). | |
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