Viessmann Boiler Fault Codes

In the unfortunate event that your Viessmann boiler develops an issue, it will display a fault code. 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 Viessmann range. Just search for the fault code that your boiler is displaying and the fault code finder will provide you with a diagnosis, this will assist you should you need to contact an engineer.

Viessmann Vitodens 050-W Fault Codes

Viessmann Vitodens 100-W Fault Codes

Viessmann Vitodens 111-W Fault Codes

Viessmann Vitodens 200-W Fault Codes

Viessmann Vitodens 222-F Fault Codes

Viessmann Vitodens 050-W Fault Codes

Displayed fault code	System characteristics	Cause	Measures
10	Constant mode	Short circuit, outside temperature sensor	Check the outside temperature sensor and lead.
18	Constant mode	Lead break, outside temperature sensor	Check the outside temperature sensor and lead.
30	Burner blocked	Short circuit, boiler water temperature sensor	Check boiler water temperature sensor.
38	Burner blocked	Lead break, boiler water temperature sensor	Check boiler water temperature sensor.
51	No DHW heating	Short circuit, outlet temperature sensor	Check sensor.
52	Burner blocked	Short circuit, flow sensor	Check connections and lead; replace sensor if required.
59	No DHW heating	Lead break, outlet temperature sensor	Check sensor.
5A	Burner blocked	Lead break, flow sensor	Check connections and lead; replace sensor if required.
A9	Control mode without OpenTherm influence	Communication error, OpenTherm device	Check connections and lead; replace OpenTherm if required.
b0	Burner blocked	Short circuit, flue gas temperature sensor	Check sensor.
b8	Burner blocked	Lead break, flue gas temperature sensor	Check sensor.
E3	Burner in a fault state	Fault in safety chain	Check the temperature limiter and connecting cables.
E5	Burner blocked	Internal fault	Check the ionisation electrode and connecting cables.
F0	Burner blocked	Internal fault	Replace control unit.
F1	Burner in a fault state	Max. flue gas temperature exceeded	Check heating system fill level. Check circulation pump. Vent the system.
F2	Burner in a fault state	Temperature limiter has responded	Check heating system fill level. Check circulation pump. Vent the system. Check the temperature limiter and connecting cables . Press "Reset"
F3	Burner in a fault state	Flame signal is al ready present at burner start	Check ionisation electrode and connecting cable. Press "Reset"
F4	Burner in a fault state	No flame signal detected	Check the ignition/ionisation electrode and connecting cables, check the gas pressure, check the gas train, ignition, ignition module and condensate drain. Press "Reset"
F8	Burner in a fault state	Fuel valve closes too late	Check gas train. Check both control paths. Press "Reset"
F9	Burner in a fault state	Fan speed too low during burner start	Check fan, fan connecting cables and power supply; check fan control. Press "Reset"
FA	Burner in a fault state	Fan idle state not reached	Check fan, fan connecting cables and power supply; check fan control. Press "Reset"
FC	Burner blocked	Electrical fan control (control unit) faulty	Check fan connecting cable; replace if required, or replace control unit.
Fd	Burner blocked	Fault, burner control unit sensor	Check ignition electrodes and connecting cables. Check whether a strong interference (EMC) field exists near the appliance. Press "Reset" . Replace control unit if fault persists.
FF	Burner blocked	Fault, burner control unit sensor	Check ignition electrodes and connecting cables. Check whether a strong interference (EMC) field exists near the appliance. Press "Reset" . Replace control unit if fault persists.
–––	Burner blocked	Communication error between burner control unit and programming unit	Check connecting cable. Press "Reset". Replace burner control unit or programming unit if the fault persists

Viessmann Vitodens 100-W Fault Codes

Displayed fault code	System characteristics	Cause	Measures
10	Constant mode	Short circuit, outside temperature sensor	Check the outside temperature sensor and lead.
18	Constant mode	Lead break, outside temperature sensor	Check the outside temperature sensor and lead.
30	Burner blocked	Short circuit, boiler water temperature sensor	Check boiler water temperature sensor.
38	Burner blocked	Lead break, boiler water temperature sensor	Check boiler water temperature sensor.
51	No DHW heating	Short circuit, outlet temperature sensor	Check sensor.
52	Burner blocked	Short circuit, flow sensor	Check connections and lead; replace sensor if required.
59	No DHW heating	Lead break, outlet temperature sensor	Check sensor.
5A	Burner blocked	Lead break, flow sensor	Check connections and lead; replace sensor if required.
A9	Control mode without OpenTherm influence	Communication error, OpenTherm device	Check connections and lead; replace OpenTherm if required.
b0	Burner blocked	Short circuit, flue gas temperature sensor	Check sensor .
b8	Burner blocked	Lead break, flue gas temperature sensor	Check sensor.
E3	Burner in a fault state	Fault in safety chain	Check the temperature limiter and connecting cables.
E5	Burner blocked	Internal fault	Check the ionisation electrode and connecting cables.
F0	Burner blocked	Internal fault	Replace control unit.
F1	Burner in a fault state	Max. flue gas temperature exceeded	Check heating system fill level. Check circulation pump. Vent the system.
F2	Burner in a fault state	Temperature limiter has responded	Check heating system fill level. Check circulation pump. Vent the system. Check the temperature limiter and connecting cables. Press "Reset".
F3	Burner in a fault state	Flame signal is al ready present at burner start sensor	Check ionisation electrode and connecting cable. Press "Reset" burner start.
F4	Burner in a fault state	No flame signal detected	Check the ignition/ionisation electrode and connecting cables, check the gas pressure, check the gas train, ignition, ignition module and condensate drain. Press "Reset .
F8	Burner in a fault state	Fuel valve closes too late	Check gas train. Check both control paths. Press "Reset.
F9	Burner in a fault state	Fan speed too low during burner start	Check fan, fan connecting cables and power supply; check fan control. Press "Reset.
FA	Burner in a fault state	Fan idle state not reached	Check fan, fan connecting cables and power supply; check fan control. Press "Reset.
FC	Burner blocked	Electrical fan control (control unit) faulty	Check fan, fan connecting cables and power supply; check fan control. Press "Reset.
Fd	Burner blocked	Fault, burner control unit sensor	Check ignition electrodes and connecting cables. Check whether a strong interference (EMC) field exists near the appliance. Press "Reset". Replace control unit if fault persists
FF	Burner blocked	Fault, burner control unit sensor	Check ignition electrodes and connecting cables. Check whether a strong interference (EMC) field exists near the appliance. Press "Reset". Replace control unit if fault persists
–––	Burner blocked	Communication error between burner control unit and programming unit	Check connecting cable. Press "Reset. Replace burner control unit or programming unit if the fault persists.

Viessmann Vitodens 111-W Fault Codes

Fault code displayed	System characteristics	Cause	Measures
0A	Burner blocked	CO limiter (if installed) has responded. CO concentration too high.	Check the heating system. Remove the cause of escaping CO.
0A	Burner blocked	Gas pressure switch (if installed) has responded. Gas pressure too low.	Check the gas supply.
0C	Burner blocked	Mains voltage too low	Check the power supply.
10	Continuous operation	Short circuit, outside temperature sensor	Check the outside temperature sensor and lead .
18	Continuous operation	Lead break, outside temperature sensor	Check the outside temperature sensor and lead .
30	Burner blocked	Short circuit, boiler water temperature sensor	Check boiler water temperature sensor.
38	Burner blocked	Lead break, boiler water temperature sensor	Check boiler water temperature sensor.
50	No DHW heating	Short circuit, cylinder temperature sensor	Check sensor.
51	No DHW heating	Short circuit, cylinder outlet sensor	Check sensor.
58	No DHW heating	Lead break, cylinder temperature sensor	Check sensor.
59	No DHW heating	Lead break, outlet temperature sensor	Check sensor.
A3	Burner blocked.	Flue gas temperature sensor incorrectly positioned.	Fit flue gas temperature sensor correctly.
A9	Control mode without OpenTherm device	Communication error, OpenTherm device	Check connections and lead; replace OpenTherm device if required.
b0	Burner blocked	Short circuit, flue gas temperature sensor	Check sensor.
b7	Emergency mode	Burner control unit fault	Turn the ON/OFF switch OFF and ON again.
b8	Burner blocked	Lead break, flue gas temperature sensor	Check sensor.
E3	Burner in a fault state	Fault in safety chain	Check the temperature limiter and connecting cables. Check the control unit, and replace if required.
E5	Burner blocked	Internal fault	Check the ionisation electrode and connecting cables. Press reset.
F0	Burner blocked	Internal fault	Replace control unit.
F1	Burner in a fault state	Max. flue gas temperature exceeded	Check heating system fill level. Check circulation pump. Vent the system. Press reset.
F2	Burner in a fault state	Temperature limiter has responded	Check heating system fill level. Check circulation pump. Vent the system. Check the temperature limiter and connecting cables. Press reset .
F3	Burner in a fault state	Flame signal is already present at burner start	Check ionisation electrode and connecting cable. Press reset .
F4	Burner in a fault state	No flame signal detected	Check the ignition/ionisation electrode and connecting cable, the gas pressure, the gas train, ignition and condensate drain. Press reset .
F8	Burner in a fault state	Fuel valve closes too late	Check gas train. Check both control paths. Press reset .
F9	Burner in a fault state	Fan speed too low during burner start	Check fan, fan connecting cables and power supply to fan; check fan control. Press reset.
FA	Burner in a fault state	Fan idle state not reached	Check fan, fan connecting cables and fan control. Press reset.
FC	Burner blocked	Electrical fan control (control unit) faulty	Check fan connecting cable; replace if required, or replace control unit.
Fd	Burner blocked	Burner control unit fault	Check ignition electrodes and connecting cables. Check whether a strong interference (EMC) field exists near the appliance. Press reset . Replace control unit if fault persists.
FF	Burner blocked	Burner control unit fault	Check ignition electrodes and connecting cables. Check whether a strong interference (EMC) field exists near the appliance. Press reset . Replace control unit if fault persists.

Viessmann Vitodens 200-W Fault Codes

Fault code displayed	System characteristics	Cause	Measures
10	Regulates as if the outside temperature were 0 °C.	Short circuit, outside temperature sensor	Check outside temperature sensor.
18	Regulates as if the outside temperature were 0 °C.	Lead break, outside temperature sensor	Check outside temperature sensor.
19	Regulates as if the outside temperature were 0 °C.	Communication interruption, outside temperature sensor RF	Check wireless connection. Place outside temperature sensor RF close to the boiler. Forget outside temperature sensor, then pair again .Replace outside temperature sensor RF.
20	Regulates without flow temperature sensor (low loss header).	Short circuit, system flow temperature sensor	Check low loss header sensor .
21	Control mode Display fault in energy cockpit	Sensor outside tolerance range	Check sensors on DHW cylinder and collectors.
22	Control mode Display fault in energy cockpit	Sensor outside tolerance range	Check sensors on DHW cylinder and collectors.
23	Control mode Display fault in energy cockpit	Incorrect commissioning	Determine solar circuit flow rate and enter value established.
24	Control mode Display fault in energy cockpit	DHW circulation pump shut down	Check setting of parameter 39 ("General" group). If required, carry out an actuator test.
25	Control mode Display fault in energy cockpit	Transfer pump not working	Check setting of parameter 20 ("Solar" group). If required, carry out an actuator test.
26	Control mode Display fault in energy cockpit	DHW circulation pump and transfer pump not working	Check settings of parameter 39 ("General" group) and parameter 20 ("Solar" group). If required, carry out an actuator test.
27	Control mode Display fault in energy cockpit	Incorrect commissioning	Determine solar circuit flow rate and enter value established.
28	Regulates without flow temperature sensor (low loss header).	Lead break, system flow temperature sensor	Check low loss header sensor If no low loss header sensor is connected, set parameter 52:0.
2A	Control mode Display fault in energy cockpit	Solar circuit flow and return interchanged.	Check solar circuit flow and return and swap over if required.
30	Burner blocked	Short circuit, boiler water temperature sensor	Check boiler water temperature sensor .
38	Burner blocked	Lead break, boiler water temperature sensor	Check boiler water temperature sensor.
40	Mixer closes.	Short circuit, flow temperature sensor, heating circuit 2 (with mixer)	Check flow temperature sensor.
44	Mixer closes.	Short circuit, flow temperature sensor, heating circuit 3 (with mixer)	Check flow temperature sensor.
48	Mixer closes.	Lead break, flow temperature sensor, heating circuit 2 (with mixer)	Check flow temperature sensor.
49	Mixer closes.	Incorrect assignment of extension for mixer, heating circuit 2	Check and adjust rotary selector S1.
4C	Mixer closes.	Lead break, flow temperature sensor, heating circuit 3 (with mixer)	Check flow temperature sensor .
4D	Mixer closes.	Incorrect assignment of extension for mixer, heating circuit 3	Check and adjust rotary selector S1.
50	No DHW heating by the boiler	Short circuit, cylinder temperature sensor or comfort sensor	Check cylinder temperature sensor or comfort sensor.
51	No DHW heating by the boiler	Short circuit, outlet temperature sensor	Check outlet temperature sensor.
58	No DHW heating by the boiler	Lead break, cylinder temperature sensor or comfort sensor	Check cylinder temperature sensor or comfort sensor .
59	No DHW heating by the boiler	Lead break, outlet temperature sensor	Check outlet temperature sensor.
90	Control mode	Short circuit, temperature sensor	Check sensor on solar control module.
91	Control mode	Short circuit, temperature sensor	Check sensor on solar control module.
92	No solar DHW heating	Short circuit, collector temperature sensor	Check temperature sensor on solar control module or sensor on the Vitosolic.
93	Control mode	Short circuit, collector return temperature sensor	Check temperature sensor at terminal S3 on the Vitosolic 100.
94	No solar DHW heating	Short circuit, cylinder temperature sensor	Check temperature sensor on solar control module or sensor on the Vitosolic.
95	Burner blocked	CO limit exceeded	Danger An increased concentration of carbon monoxide can cause potentially fatal car- bon monoxide poisoning. Observe the safety instructions at the beginning of this manual. Determine the cause of the increased CO level. Remedy the fault. Press Test on the CO limiter. The alarm is switched off. The burner starts again once the CO level is below the CO limit.
96	Burner blocked	CO limiter sensor fault	Replace the CO limiter. If the system is to be temporarily operated without CO limiter, set parameter 49:0.
98	Control mode	Lead break, temperature sensor	Check sensor on solar control module.
99	Control mode	Lead break, temperature sensor	Check sensor on solar control module.
9A	No solar DHW heating	Lead break, collector temperature sensor	Check temperature sensor on solar control module or sensor on the Vitosolic.
9B	Control mode	Lead break, collector return temperature sensor	Check temperature sensor at terminal S3 on the Vitosolic 100.
9C	No solar DHW heating	Lead break, cylinder temperature sensor	Check temperature sensor on solar control module or sensor on the Vitosolic.
9E	Control mode	No flow rate in solar circuit or flow rate too low, or temperature limiter has responded.	Check solar circuit pump and solar circuit. Acknowledge fault message.
9F	Control mode	Solar control module or Vitosolic fault	Replace solar control module or Vitosolic.
A3	Burner blocked	Flue gas temperature sensor incorrectly positioned	Fit flue gas temperature sensor correctly.
A7	Control mode as per delivered condition	Programming unit faulty	Replace the programming unit.
A8	Burner blocked. The venting program is started automatically.	Air in the internal circulation pump or minimum flow rate not achieved	Vent the system if the fault message persists.
A9	If a heating circuit with mixer is connected, the burner operates at its lower heating output. If only one heating circuit without mixer is connected, the burner is blocked.	Internal circulation pump blocked	Check circulation pump.
B0	Burner blocked	Short circuit, flue gas temperature sensor	Check flue gas temperature sensor.
B1	Control mode as per delivered condition	Communication error, programming unit	Check connections; replace programming unit if necessary.
B5	Control mode as per delivered condition	Internal fault	Replace control unit.
B7	Burner blocked	Boiler coding card fault	Plug in boiler coding card or replace if faulty.
B8	Burner blocked	Lead break, flue gas temperature sensor	Check flue gas temperature sensor.
BA	Mixer regulates to 20 °C flow temperature.	Communication error, extension kit for heating circuit 2 (with mixer)	Check extension kit connections and assignment.
BB	Mixer regulates to 20 °C flow temperature.	Communication error, extension kit for heating circuit 3 (with mixer)	Check extension kit connections and assignment.
BC	Control mode without remote control	Communication error, Vitotrol remote control, heating circuit 1 (without mixer)	Check connections, cable, parameter "A0" in the "Heating circuit" group and remote control settings . For wireless remote controls: check connection, place remote control close to the boiler.
BD	Control mode without remote control	Communication error, Vitotrol remote control, heating circuit 2 (with mixer)	Check connections, cable, parameter "A0" in the "Heating circuit" group and remote control settings . For wireless remote controls: check connection, place remote control close to the boiler.
BE	Control mode without remote control	Communication error, Vitotrol remote control, heating circuit 3 (with mixer)	Check connections, cable, parameter "A0" in the "Heating circuit" group and remote control settings . For wireless remote controls: check connection, place remote control close to the boiler.
BF	Control mode	Incorrect LON communication module	Replace LON communication module.
C1	Control mode	Communication error, EA1 extension	Check connections.
C2	Control mode	Communication error, solar control module or Vitosolic	Check solar control module or Vitosolic.
C3	Control mode	Communication error, AM1 extension	Check connections.
C4	Control mode	Communication error, OpenTherm extension	Check OpenTherm extension.
C5	Control mode, max. pump speed	Communication error, internal variable speed pump	Check setting of parameter "30" in "Boiler" group.
CD	Control mode	Communication error, Vitocom 100 (KM-BUS)	Check connections, Vitocom 100 and parameter "95" in "General" group.
CF	Control mode	Communication error, communication module	Replace communication module.
D3	Burner in a fault state or blocked.	Communication error, fan unit	Check the connecting cable to the fan unit. Press reset button R. If the fault recurs, replace the fan unit.
D4	Control mode Burner is operating with a limited modulation range.	No air flow detected in fan unit.	Check the mass flow sensor at the fan unit. Check the flue system for flue gas back pressure.
D5	Burner in a fault state.	Fan blocked	Press reset button R. Check free movement of the impeller. Replace the fan unit if required.
D6	Control mode	Input DE1 at EA1 extension reports a fault.	Remedy fault at appliance concerned.
D7	Control mode	Input DE2 at EA1 extension reports a fault.	Remedy fault at appliance concerned.
D8	Control mode	Input DE3 at EA1 extension reports a fault.	Remedy fault at appliance concerned.
DA	Control mode without room influence	Short circuit, room temperature sensor, heating circuit 1 (without mixer)	Check room temperature sensor, heating circuit 1. External room temperature sensor for Vitotrol 300 or integrated sensor for Vitotrol 200/300
DB	Control mode without room influence	Short circuit, room temperature sensor, heating circuit 2 (with mixer)	Check room temperature sensor, heating circuit 2. External room temperature sensor for Vitotrol 300 or integrated sensor for Vitotrol 200/300
DC	Control mode without room influence	Short circuit, room temperature sensor, heating circuit 3 (with mixer)	Check room temperature sensor, heating circuit 3. External room temperature sensor for Vitotrol 300 or integrated sensor for Vitotrol 200/300
DD	Control mode without room influence	Lead break, room temperature sensor, heating circuit 1 (without mixer)	Check room temperature sensor, heating circuit 1 and remote control settings . External room temperature sensor for Vitotrol 300 or integrated sensor for Vitotrol 200/300
DE	Control mode without room influence	Lead break, room temperature sensor, heating circuit 2 (with mixer)	Check room temperature sensor, heating circuit 2 and remote control settings. External room temperature sensor for Vitotrol 300 or integrated sensor for Vitotrol 200/300
DF	Control mode without room influence	Lead break, room temperature sensor, heating circuit 3 (with mixer)	Check room temperature sensor, heating circuit 3 and remote control settings ). External room temperature sensor for Vitotrol 300 or integrated sensor for Vitotrol 200/300
E0	Control mode	External LON subscriber error	Check connections and LON subscribers.
E2	Burner in a fault state	No calibration as flow rate too low	Ensure adequate heat transfer. Press reset button R.
E3	Burner in a fault state	Heat transfer too low during calibration Temperature limiter has shut down.	Ensure adequate heat transfer. Press reset button R.
E4	Burner blocked	24 V power supply fault	Replace control unit.
E5	Burner blocked	Flame amplifier fault	Replace control unit.
E8	Burner in a fault state	Ionisation current lies out- side the permissible range	Check gas supply (gas pressure and gas flow switch), gas train and connecting cable. Check assignment of gas type. Check ionisation electrode: ■ Distance to burner gauze assembly (see page 42) ■ Electrode soiled Press reset button R.
EB	Burner in a fault state	Repeated flame loss or deactivation during calibration	1. Check system for excessive temperature. If fault F1 or F2 is present, ensure there is adequate heat transfer. Press reset button R. 2. Check system for condensate backup. Note To prevent water damage, detach fan unit before removing the burner. Remove the condensate back- up. Press reset button R. 3. Check ionisation electrode for contamination. Check gap between ionisation electrode and burner gauze assembly (see page 42). Press reset button R. 4. Check flue system; remove flue gas recirculation if required. Press reset button R.
EC	Burner in a fault state	Parameter error during calibration	Press reset button R. or Replace boiler coding card and press reset button R.
ED	Burner in a fault state	Internal fault	Replace control unit.
EE	Burner in a fault state	Flame signal at burner start not present or insufficient.	■ Check gas supply (gas pressure and gas flow switch). ■ Check gas train. ■ Check system for condensate backup. Note To prevent water damage, detach fan unit before removing the burner. ■ Check ionisation electrode and connecting cable. Check ignition: ■ Connecting cables to ignition module and ignition electrode ■ Ignition electrode gap and soiling (see page 42). Press reset button R.
EF	Burner in a fault state	Flame is lost immediately after it has built (during safety time).	Check gas supply (gas pressure and gas flow switch). Check balanced flue system for flue gas recirculation. Check ionisation electrode (replace if required): ■ Distance to burner gauze assembly (see page 42) ■ Electrode soiled Press reset button R.
F0	Burner blocked	Internal fault	Replace control unit.
F1	Burner in a fault state	Flue gas temperature limiter has responded.	Check heating system fill level. Vent the system. When the flue system has cooled down, press reset button R.
F2	Burner in a fault state	Temperature limiter has responded.	Check heating system fill level. Check circulation pump. Vent the system. Check temperature limiter and connecting cables. Press reset button R.
F3	Burner in a fault state	Flame signal is already present at burner start.	Check ionisation electrode and connecting cable. Check system for condensate backup. Note To prevent water damage, detach fan unit before removing the burner. Press reset button R.
F8	Burner in a fault state	Fuel valve or modulation valve will not close.	Check the gas train and replace if required. Press reset button R.
F9	Burner in a fault state	Fan speed too low	Check fan, fan connecting cables and fan power supply. Press reset button R.
FA	Burner in a fault state	Fan idle state or set speed not reached	Check fan, check connecting cables to fan. Press reset button R.
FC	Burner in a fault state	Fan unit faulty.	Check fan unit, replace if required. Press reset button R.
Fd	Burner in a fault state and additional fault B7 is displayed.	Boiler coding card missing.	Insert the boiler coding card. Press reset button R. Replace control unit if fault persists.
Fd	Burner in a fault state	Burner control unit fault	Check ignition electrode, ionisation electrode and connecting cables. Check whether a strong interference (EMC) field exists near the appliance. Press reset button R. If the fault occurs sporadically, replace the coding card. Replace control unit if fault is permanent.
FE	Burner blocked or in a fault state	Boiler coding card or main PCB faulty, or incorrect boiler coding card	Press reset button R. If the fault persists, check the boiler coding card and replace boiler coding card or control unit if necessary.
FF	Burner blocked or in a fault state	Internal fault or reset button R blocked.	Restart the appliance. Replace the control unit if the appliance will not restart.

Viessmann Vitodens 222-F Fault Codes

Displayed fault code	Const.	Weath.- comp.	System characteristics	Cause	Measures
10	X	X	Regulates as if the outside temperature were 0 °C	Short circuit, outside temperature sensor	Check the outside temperature sensor.
18	X	X	Regulates as if the outside temperature were 0 °C	Lead break, outside temperature sensor	Check the outside temperature sensor.
20	X	X	Regulates without flow temperature sensor (low loss header)	Short circuit, system flow temperature sensor	Check the low loss header sensor.
28	X	X	Regulates without flow temperature sensor (low loss header)	Lead break, system flow temperature sensor	Check the low loss header sensor.
30	X	X	Burner blocked	Short circuit, boiler water temperature sensor	Check the boiler water temperature sensor .
38	X	X	Burner blocked	Lead break, boiler water temperature sensor	Check the boiler water temperature sensor .
40		X	Mixer closes	Short circuit, flow temperature sensor, heating circuit 2 (with mixer)	Check flow temperature sensor
44		X	Mixer closes	Short circuit, flow temperature sensor, heating circuit 3 (with mixer)	Check flow temperature sensor
48		X	Mixer closes	Lead break, flow temperature sensor, heating circuit 2 (with mixer)	Check flow temperature sensor
4C		X	Mixer closes	Lead break, flow temperature sensor, heating circuit 3 (with mixer)	Check flow temperature sensor
50	X	X	No DHW heating	Short circuit, cylinder temperature sensor	Check sensors
51	X	X	No DHW heating	Short circuit, outlet temperature sensor	Check sensors
58	X	X	No DHW heating	Lead break, cylinder temperature sensor	Check sensors
59	X	X	No DHW heating	Lead break, outlet temperature sensor	Check sensors
A7		X	Control mode as per delivered condition	Programming unit faulty	Replace programming unit
A9		X	The burner operates at its lower output if a heating circuit with mixer is connected. The burner is blocked if only one heating circuit without mixer is connected.	Internal circulation pump blocked	Check the circulation pump
b0	X	X	Burner blocked	Short circuit, flue gas temperature sensor	Check the flue gas temperature sensor
b1	X	X	Control mode as per delivered condition	Communication error, programming unit	Check connections and replace the programming unit if required
b5	X	X	Control mode as per delivered condition	Internal fault	Replace the control unit
b7	X	X	Burner blocked	Boiler coding card faulty	Plug in boiler coding card or replace, if faulty
b8	X	X	Burner blocked	Lead break, flue gas temperature sensor	Check the flue gas temperature sensor
bA		X	Mixer regulates to a flow temperature of 20 °C	Communication error, extension kit for heating circuit 2 (with mixer)	Check extension kit connections and code
bb		X	Mixer regulates to a flow temperature of 20 °C	Communication error, extension kit for heating circuit 3 (with mixer)	Check extension kit connections and code
bC		X	Control mode without remote control	Communication error, remote control Vitotrol heating circuit 1 (without mixer)	Check connections, lead, coding address "A0" and remote control settings
bd		X	Control mode without remote control	Communication error, remote control Vitotrol heating circuit 2 (with mixer)	Check connections, lead, coding address "A0" and remote control settings
bE		X	Control mode without remote control	Communication error, remote control Vitotrol heating circuit 3 (with mixer)	Check connections, lead, coding address "A0" and remote control settings
bF		X	Control mode	Incorrect LON communication module	Replace the LON communication module
C1	X	X	Control mode	Communication error extension EA1	Check electrical connections
C3	X	X	Control mode	Extension AM1 communication error	Check electrical connections
C4	X	X	Control mode	Communication error, Open Thermextension	Check Open Therm extension
C5	X	X	Control mode, max. pump speed	Communication error, variable speed internal pump	Check the setting of coding address "30"
C6		X	Control mode, max. pump speed	Communication error, external variable speed heating circuit pump, heating circuit 2 (with mixer)	Check setting of coding address "E5"
C7	X	X	Control mode, max. pump speed	Communication error, external variable speed heating circuit pump, heating circuit 1 (without mixer)	Check setting of coding address "E5"
C8		X	Control mode, max. pump speed	Communication error, external variable speed heating circuit pump, heating circuit 3 (with mixer)	Check setting of coding address "E5"
Cd	X	X	Control mode	Communication error, Vitocom 100 (KM BUS)	Check connections, Vitocom 100 and coding address "95"
CE	X	X	Control mode	Communication error, ext. extension	Check electrical connections
CF		X	Control mode	Communication error, LON communication module	Replace the LON communication module
d6	X	X	Control mode	Input DE1 reports a fault at extension EA1	Remove fault at the appliance concerned
d7	X	X	Control mode	Input DE2 reports a fault at extension EA1	Remove fault at the appliance concerned
d8	X	X	Control mode	Input DE3 reports a fault at extension EA1	Remove fault at the appliance concerned
dA		X	Control mode without room influence	Short circuit, room temperature sensor, heating circuit 1 (without mixer)	Check room temperature sensor, heating circuit 1
db		X	Control mode without room influence	Short circuit, room temperature sensor, heating circuit 2 (with mixer)	Check room temperature sensor, heating circuit 2
dC		X	Control mode without room influence	Short circuit, room temperature sensor, heating circuit 3 (with mixer)	Check room temperature sensor, heating circuit 3
dd		X	Control mode without room influence	Lead break, room temperature sensor, heating circuit 1 (without mixer)	Check room temperature sensor for heating circuit 1 and remote control settings
dE		X	Control mode without room influence	Lead break, room temperature sensor, heating circuit 2 (with mixer)	Check room temperature sensor for heating circuit 2 and remote control settings
dF		X	Control mode without room influence	Lead break, room temperature sensor, heating circuit 3 (with mixer)	Check room temperature sensor for heating circuit 3 and remote control settings
E0		X	Control mode	Fault external LON subscriber	Check connections and LON subscribers
E4	X	X	Burner blocked	Fault, supply voltage 24 V	Replace the control unit.
E5	X	X	Burner blocked	Fault, flame amplifier	Replace the control unit.
E8	X	X	Burner in a fault state	The ionisation current lies outside the permissible range	Check the ionisation electrode and cable. Press reset button R.
EA	X	X	Burner in a fault state	The ionisation current lies outside the permissible range during calibration	Check the ionisation electrode and cable. Press reset button R.
Eb	X	X	Burner in a fault state	Heat draw-off repeatedly too low during calibration	Initiate a heat draw-off. Switch the boiler OFF and ON again. Press reset button R.
EC	X	X	Burner in a fault state	Parameter fault during calibration	Press reset button R or replace boiler coding card and press reset button R.
Ed	X	X	Burner in a fault state	Internal fault	Replace the control unit.
EE	X	X	Burner in a fault state	Flame signal is not present or too weak at burner start	Check the ionisation electrode and connecting cable, measure the ionisation current, check the gas supply (gas pressure and gas flow limiter), check the gas train, ignition, ignition module, ignition electrodes and the condensate drain. Press reset button R.
EF	X	X	Burner in a fault state	Flame is lost after flame has built.	Check the gas supply (gas pressure and gas flow limiter), check the flue gas/ventilation air system for flue gas recirculation, check the ionisation electrode (replace if required). Press reset button R.
F0	X	X	Burner blocked	Internal fault	Replace the control unit.
F1	X	X	Burner in a fault state	Flue gas temperature limiter has responded	Check the heating system fill level. Vent the system. Press reset button R after the flue system has cooled down.
F2	X	X	Burner in a fault state	The temperature limiter has responded	Check the heating system fill level. Check the circulation pump. Vent the system. Check the temperature limiter and connecting cables Press reset button R.
F3	X	X	Burner in a fault state	Flame signal is already present at burner start	Check the ionisation electrode and connecting cable. Press reset button R.
F8	X	X	Burner in a fault state	The fuel valve closes too late	Check the gas train. Check both control paths. Press reset button R.
F9	X	X	Burner in a fault state	Fan speed too low during burner start	Check the fan, the fan connecting cables and power supply; check the fan control. Press reset button R.
FA	X	X	Burner in a fault state	Fan not at standsill	Check the fan, fan connecting cables and fan control. Press reset button
FC	X	X	Burner in a fault state	Gas train faulty or faulty modulation valve control or flue gas path blocked	Check the gas train. Check the flue gas system.. Press reset button R.
Fd	X	X	Burner in a fault state	Fault, combustion controller	Check ignition electrodes and connecting cables Check whether a strong interference (EMC) field exists near the appliance. Press reset button R. Replace control unit if the fault persists.
FE	X	X	Burner blocked or in a fault state	Boiler coding card or main PCB faulty	Press reset button R. Replace boiler coding card or control unit if the fault persists.
FF	X	X	Burner blocked or in a fault state	Internal fault or reset button R blocked	Start the appliance again. Replace the control unit if the appliance will not restart.

Viessmann Boiler Fault Codes

Viessmann Vitodens 050-W Fault Codes

Viessmann Vitodens 100-W Fault Codes

Viessmann Vitodens 111-W Fault Codes

Viessmann Vitodens 200-W Fault Codes

Viessmann Vitodens 222-F Fault Codes

Viessmann Vitodens 050-W Fault Codes

Viessmann Vitodens 100-W Fault Codes

Viessmann Vitodens 111-W Fault Codes

Viessmann Vitodens 200-W Fault Codes

Viessmann Vitodens 222-F Fault Codes

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