Fault Code Identifier 

Here we have detailed the possible reasons that specific fault codes may be appearing on your Viessmann boiler. Depending on which Viessmann boiler you have, the diagnosis for the code appearing may differ. In order to correctly diagnose the fault your Viessmann boiler is experiencing, we always recommend contacting a Viessmann Trained Installer.

Fault code 0b


Boiler model
System behaviour  Diagnosis 
Vitodens 200  The burner control switches to lockout. The fan does not idel after auto reset (incorrect fan rpm) Severe wind conditions in the vent system 
Vitodens 100-W  Burner blocked   Insufficient water flow. Incorrect flow direction. Defective flow switch (blockage)

Fault code 0C


Boiler model
System behaviour  Diagnosis 
Vitodens 100-W Burner blocked  Insufficient power supply 
Vitodens 200  Burner control switches to lockout  Flame signal still present after switching off

Fault code 0F

Boiler model System behaviour  Diagnosis 
Vitodens 222-F  Control mode  Code ”0F” is only
displayed in the fault history(service required)
Vitotronic 300 / Vitotronic 300-K, with Vitotronic 300 / Vitodens 200-W / Vitocontrol-S, with Vitotronic 100 Control mode /
Controlled operation
Service required.
”0F” is only displayed in the fault history.
Vitotronic 200 / 300 Normal operation Service required
Vitocontrol-S, MW1 with Vitotronic 100 / Vitotronic 300-K, MW1S with Vitotronic 100 Control mode Maintenance ”0F” is
only displayed in the fault history

Fault code 10


Boiler model
System behaviour  Diagnosis 
Vitodens 200-W / 222-F / Vitotronic 300 / 200/ 200-H / 050/200-H / 300-K / vitocontrol-S Boiler operates based
on outdoor temperature of 32°F / 0°C
Short circuit –
Outdoor temperature sensor
Vitotronic 300-K, MW2S with Vitotronic 100 / Vitodens 100-W (combiPLUS) / 200-W / Vitocontrol-S, WB2B with Vitotronic 100 Controls as if the
outdoor temperature / Constant Mode
Outdoor temperature
sensor shorted out

Fault Code 10, 14, F3, and F4


Boiler model
System behaviour  Diagnosis 
Vitodens 200  Burner control switches to lockout  No flame signal is present 

Fault code 18 and D1


Boiler model
System behaviour  Diagnosis 
Vitodens 100 / 200-W / 222-F / Vitotronic 300-K with 100 / Vitocontrol-S Boiler operates based on outdoor temperature of 32°F / 0°C / Constant Mode Outdoor temperature sensor cable broken
Vitotronic / 100 / 200 / 300 / 050/200-H /300-K / Vitocontrol-S, MW1 with Vitotronic 100 Operates on basis of 32°F / 0°C outdoor temperature Open circuit – Outdoor temperature sensor
Vitotronic 200-H / Vitotronic 300-K, MW1B with Vitotronic 300 / Vitotronic 300-K, MW2B with Vitotronic 200 Controls as if the outdoor temperature Lead break, Outdoor temperature sensor
Vitotronic 050/200-H Activates after 0°C / 32°F outdoor temperature Cable break – Outdoor temperature sensor
Vitodens 100-W Burner in fault mode DIP switch S2 is set to “ON”

Fault code 19


Boiler model
System behaviour  Diagnosis 
Vitotronic 300  Activates after 0°C / 32°F outdoor temperature Communication fault, Wireless Outdoor temperature sensor

Fault code 20


Boiler model
System behaviour  Diagnosis 
Vitocontrol-S with Vitotronic 100 / Vitotronic 300 / 300-K / 200 / 100 Stand-alone control unit without supply temperature sensor (possibly supply temperature not high enough) Short circuit – Common supply temperature sensor
Vitocontrol-S with Vitotronic 100 / Vitotronic 300-K, with Vitotronic 200 Vitocontrol-S, controls in a stand-alone manner w/o supply temperature sensor (supply temperature may not be high enough) Common supply temperature sensor shorted out
Vitocrossal 300 Regulates without supply temperature sensor (low-loss header) Short circuit – System Flow temperature sensor
Vitodens 200-W / 222-F Regulates without supply temperature sensor (low-loss header) Short circuit – System supply temperature sensor
Vitotronic 050/200-H< / 200 / 200-H / 300 Mixing valve closes/closed Short circuit – Supply temperature sensor /
mixing valve circuit M1
Vitotronic 300-K, with Vitotronic 100 Vitotronic 300-K, MW1S controls in a stand-alone manner w/o strap-on sensor (supply temperature may not be high enough)
Short circuit – Strap-on temperature sensor
Vitodens 200-W Regulates without supply temperature sensor (low-loss header) System supply temperature sensor shorted out

Fault code 21


Boiler model
System behaviour  Diagnosis 
Vitotronic 200 / 300 Operation without influence of return water temperature Short circuit – Return water temperature sensor

Fault code 28


Boiler model
System behaviour  Diagnosis 
Vitocontrol-S with Vitotronic 100  Vitocontrol-S, VD2/CT3/CM2 controls in a stand-alone manner w/o supply temperature sensor (supply temperature may not be high enough)
Open circuit – Common supply temperature sensor
Vitocontrol-S with Vitotronic 100 / Vitotronic 300-K, with Vitotronic 100 Vitocontrol-S, WB2B controls in a stand-alone manner w/o supply temperature sensor (supply temperature may not be high enough) Common supply temperature sensor cable broken
Vitocrossal 300 / Vitodens 200-W / 222-F Regulates without supply temperature sensor (low-loss header) System supply temperature sensor cable broken
Vitotronic 050/200-H Mixing valve closes Cable break – Supply temperature sensor
Vitotronic 050/200-H Mixing valve is closed Open circuit – Supply temperature sensor of
mixing valve circuit M1
Vitotronic 200-H / Vitotronic 200 / 300 Mixing valve is being closed Lead break, Supply temperature sensor, heating circuit with mixing valve M1 (heating circuit 1)
Vitotronic 300 Vitotronic / 300-K with Vitotronic 300 / 200 Stand-alone control unit without supply temperature sensor (possibly supply temperature not high enough) Lead break, Common supply temperature sensor
Vitotronic 300-K with Vitotronic 100 Vitotronic 300-K, MW1S controls in a stand-alone manner w/o strap-on sensor (supply temperature may not be high enough) Open circuit – Strap-on temperature sensor

Fault Code 29, 41, 49, F-80, F-81, F-83, F-88 and F-89


Boiler model
System behaviour  Diagnosis 
Vitotronic 200 / 300 Normal operation without influence of return water temperature Open circuit 1 or 2 – Return water temperature sensor (of mixing valve circuit 1)

Fault code 30


Boiler model
System behaviour  Diagnosis 
Vitocontrol-S, with Vitotronic 100 / Vitocrossal 300 / Vitodens 200-W / 222-F / Vitotronic 100 / 200 / 300 Burner is started and stopped via an adjustable high limit Short circuit – Boiler water temperature sensor
Vitocontrol-S with Vitotronic 100 / Vitodens100-W (CombiPLUS)/ 200-1 Burner blocked Boiler water temperature sensor shorted out

Fault code 38


Boiler model
System behaviour  Diagnosis 
Vitodens – 200-W / 222-F / COMBIPLUS Burner blocked Boiler water temperature sensor cable broken
Vitotronic 100 / 200 / 300 / Vitocontrol-S with Vitotronic 100 Burner is switched on and off by the adjustable high limit Open circuit – Boiler temperature sensor
Vitotronic 300-K with Vitotronic 300 /Vitotronic 300-K with Vitotronic 300 The burner is started and stopped via a temperature controller Lead break, Boiler water temperature sensor
Vitodens 100-W Burner blocked Boiler water temperature sensor lead broken

Fault code 40 and 44

Boiler model  System behaviour  Diagnosis 
All Viessmann boilers Mixing valve closes Heating circuit 2 with mixing valve supply short circuit on temperature sensor

 

Fault code 41


Boiler model
System behaviour  Diagnosis 
Vitotronic 300 Operation without accounting for return water temperature Short circuit – Return water temperature sensor of mixing valve circuit 2

Fault Code 48 and 4C

Boiler model  System behaviour  Diagnosis 
All Viessmann boilers Mixing valve closes / Closed Heating circuit 2 with mixing valve supply
temperature sensor cable broken / open circuit

Fault Code 50, 51, 58 and 59


Boiler model
System behaviour  Diagnosis 
Vitodens 200-W / 222-F No DHW heating/ Fault with DHW Short circuit/open circuit – DHW tank temperature sensor or lead break

Fault code 52


Boiler model
System behaviour  Diagnosis 
Vitotronic 300 Control mode Short circuit –Supply temperature sensor low-loss header
Vitodens 100-W CombiPLUS Burner blocked (with
CombiPLUS only)
Flow sensor shorted out (in CombiPLUS)

Fault Code 55, 56 and 57


Boiler model
System behaviour  Diagnosis 
Vitotronic 300-K,
with Vitotronic 200
Control mode Maintenance or fault on Vitotronic 100 of boiler 5-8

Fault Code 5A, B7, and B8


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers Control mode Lead break, low-loss
header Supply temperature sensor
All Viessmann boilers Burner blocked /
control mode
Sensor cable broken

Fault code 5C, 5D, 5E and 5F


Boiler model
System behaviour  Diagnosis 
Vitotronic 300-K with Vitotronic 200 Control mode Communication fault, Vitotronic 100 of boiler
5-8

Fault Code 60, 68, 70, 78, BD, BE and BF


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers

– No output reduction

– Return control open

– Boiler with maximum temperature

Short/open circuit – Temperature sensor [17A]

Fault Code 80, 81, 82, 83 and FD

Boiler model  System behaviour  Diagnosis 
All Viessmann boilers Burner control unit in a fault state; system cools down; burner control unit locked out Short circuit – Boiler water temperature sensor, burner control unit

Fault Code 88, 89, and E6


Boiler model
System behaviour  Diagnosis 
Vitotronic 300 Burner control unit in a fault state Lead break, Boiler water temperature sensor, burner control unit

Fault Code 90, 91, 92, 93, 94, 98, 99, 9A, 9B , 9C, 9E, 9F and AB


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers Control mode Short circuit –
Temperature sensor [5] / [6] / [7] / [10]

Fault Code 8C, 8D, 8E and 8F

Boiler model  System behaviour  Diagnosis 
Vitocontrol-S with Vitotronic 100 / Vitotronic 300-K with Vitotronic 100 / 200 Control mode Communication fault,
Vitotronic 100 of boiler 1-4

Fault Code A0, A1, A2, AA, and AC

Boiler model  System behaviour  Diagnosis 
Vitotronic 300 / Vitotronic 300-K with Vitotronic 300 Boiler cools down Fault, safety equipment at ” X2 / X3 / X7″ of plug-in adaptor 2 for external safety equipment
Vitodens 200 Boiler operates in emergency mode
(after approx. 30 min. BUS fault) OR Boiler cools down
Internal BUS fault OR
Open circuit – Internal BUS connection

Fault code A4


Boiler model
System behaviour  Diagnosis 
Vitodens 200 Pump runs at maximum speed Open circuit – BUS connection with variable speed heating circuit pump

Fault Code A3, B0, F1, F-E1 and F-E2


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers Burner blocked

Flue gas temperature sensor not properly positioned / Check Sensor

External pump fitted on the system(100-w) A-3 fault.

Fault code A7


Boiler model
System behaviour  Diagnosis 
Vitocrossal 300 / Vitodens 200-W / 222-F / 300 Control mode (stays in factory default setting) Faulty programming unit

Fault code A8 


Boiler model
System behaviour  Diagnosis 
Vitodens 222-F Burner blocked. The venting program is started automatically Air lock in the internal circulation pump or minimum flow rate not achieved

Fault Code A9, BA, BB, BC and F-E0

Boiler model  System behaviour  Diagnosis 
All Viessmann boilers Control mode Communication fault

Fault code AD


Boiler model
System behaviour  Diagnosis 
Vitocontrol-S with Vitotronic 100 / Vitotronic 100 / Vitotronic 300-K with Vitotronic 300 Control mode Isolation valveconfiguration fault: Coding OC:2, OC:3 or OC:4 set, and coding 4E:1 not set

Fault code B1

Boiler model  System behaviour  Diagnosis 
All Viessmann boilers Control mode Communication fault,
Programming unit

Fault code B2


Boiler model
System behaviour  Diagnosis 
Vitodens 200 Boiler cools down Sensor inputs are not
read correctly

Fault Code B3 and E5


Boiler model
System behaviour  Diagnosis 
Vitodens 200 Setting via service level not possible Data points are not stored; internal fault VR20

Fault code B4


Boiler model
System behaviour  Diagnosis 
Vitocontrol-S with Vitotronic 100 / Vitotronic 100 / 200 / 300 / Vitotronic 300-K with Vitotronic 100 Emissions test mode Internal electronics
fault
Vitocontrol-S with Vitotronic 100 / Vitodens 200-W Regulates as if the
outside temperature was 32°F (0°C)
Internal fault
Vitotronic 050/200-H Undefined control
characteristics
Internal electronics fault

Fault code B5


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers Control mode Internal electronics fault

Fault code B6


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers Constant mode Invalid hardware recognised

Fault Code B9, ED, F0, F-E5, F-EC, F-ED, F-EE, F-EF, F-FD and F-FF


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers Normal operation /
fault around burner control unit
Internal fault (PCB)

Fault code C1

Boiler model  System behaviour  Diagnosis 
All Viessmann boilers Control model External safety equipment

Fault Code C2-C8, CD-CF, D2-D8, DA-DF and E0


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers Control mode Open circuit – KM BUS to solar control unit / Extension AM1 / DE1-DE3 M1 / communication fault

Fault Code C9, CA and CB


Boiler model
System behaviour  Diagnosis 
Vitocontrol-S with Vitotronic 100 / Vitotronic 100/ 300 / Vitotronic 300-K with Vitotronic 300 Boiler cools down Fault: Maximum
pressure limiter 1 2

 

Fault Code CC and F0


Boiler model
System behaviour  Diagnosis 
Vitodens 200 Burner control unit switches to lockout (due to large line voltage fluctuations) Differential air pressure sensor / open circuit

Fault code D4


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers Boiler cools down Fixed high limit has responded or fuse F2 has blown.

Fault code D5


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers Boiler drives up to electronic maximum limit Boiler does not log
in at the cascade control unit

Fault Code E1, E7, E8, E9, EA, EB, EC and F2


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers Burner in fault mode

Ionisation current too high during calibration

Boiler temperature limiter responded(F2) air or blockage in system/pump failure

Fault Code E2 and E3


Boiler model
System behaviour  Diagnosis 
Vitodens 200-W /
222-F / Vitotronic 300
Burner in fault mode Heating water flow rate too low during calibration; flow switch caused shutdown

Fault code E4


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers Burner blocked Fault, supply voltage
24V

Fault Code EE and EF


Boiler model
System behaviour  Diagnosis 
Vitocontrol-S with
Vitotronic 100 / Vitocrossal 300 / Vitodens 200-W / 222-F / Vitotronic 300
Burner in fault mode At burner start,
flame signal is missing or too weak

Fault Code F5


Boiler model
System behaviour  Diagnosis 
Vitodens 100-W / 200
/ 0 / Vitotronic 300
Burner blocked
Faulty Air pressure switch. Air damper (flap) stuck

Fault Code F6, 58, F9, F-E1, F-E2 and F-F6


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers Gas pressure switch shows no gas pressure / Electrical connection fault Gas shut-off valve closed; gas pressure switch faulty; multiple problems with gas supply

Fault Code FA and FB


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers Burner in fault mode
/ Emergency operation
Fan not at standstill
/ plug-in connection

Fault Code F-B7, F-F4, F-F2, F-F7, F-F8 and F-F9


Boiler model
System behaviour  Diagnosis 
Vitocrossal 200

Case A: Burner control unit in a fault state; system cools down; burner control unit locked out.

Case B: Type of coding card

Case A: Coding card not inserted in the burner control unit; incorrect or faulty coding card.

Case B: Coding card
does not match burner control unit.

Fault Code FC

Boiler model  System behaviour  Diagnosis 
All Viessmann boilers Burner in fault mode

Gas valve faulty or faulty modulation valve control; or vent system blocked.

Check fan, fan cable, PCB

Fault code FE


Boiler model
System behaviour  Diagnosis 
All Viessmann boilers Burner blocked or in
fault mode
Strong interference
(EMC) field nearby, or Faulty main PCB

Fault Code F-E4


Boiler model
System behaviour  Diagnosis 
Vitocrossal 200 Burner shuts down Multiple detection of
undervoltage

Fault Code F-FA, F-FB and FR

Boiler model  System behaviour  Diagnosis 
Vitocrossal 200 /
400-620 / 186-311
Fan runs without demand; burner control unit in a fault state Fan has not stopped;
cable [100A] faulty; fan faulty; burner control unit faulty