Viessmann Boiler Fault Codes & Common Issues
Has your Viessmann boiler produced an error code? If that is the case, although this can appear a daunting prospect, don't worry, there may be a quick solution.
On this page you can find a list of all the Viessmann boiler fault codes and the models that it applies too. Each of these codes has a potential cause which should help you get to the bottom of what the issue is. If you are stuck and can't find the issue then our expert boiler engineer partners may be able to help, simply fill out the quick form above and they will be in contact to try and help you find a solution.
General Faults & Errors
This section is an overview of all of the types of errors that can occur on a Viessmann boilers.
| Fault Code | Behaviour | Potential Cause | Model(s) Affected |
|---|---|---|---|
| 0A | The controls switch to lockout | The fan speed is faulty | Vitodens 200 |
| 0B | Blocked burner | Flow direction incorrect Water flow insufficient Flow switch is defective | Vitodens 100-W |
| 0B | The fan RPM is not correct and it doesn't idle after reset The burner control switches to lockout | The vent system has been effected by severe wind conditions | Vitodens 200 |
| 0C | Blocked burner | The power supply is insufficient | Vitodens 100-W |
| 0C | The burner control switches to lockout | After switching off the flame signal was still present | Vitodens 200 |
| 0D | The controls switch to lockout | whilst the burner is active or the reset button has been pressed repeatedly | Vitodens 200 |
| 0F | Control mode | Maintenance, displayed in the fault history | Vitotronic 100, 300-K with MW1 & MW1S Vitocontrol-S |
| 0F | Controlled operation / mode | Service is required | Vitotronic 100, 300, 330-K Vitodens 200-W Vitocontrol-S |
| 0F | Control mode | Displayed in the fault history | Vitodens 222-F |
| 0F | Operation normal | Service is required | Vitotronic 200, 300 |
| 1A, 1B | Blocked burner | Faulty flow sensor | Vitodens 200 |
| 1F | Blocked burner | The flow rate is too large | Vitodens 200 |
| 02 | The controls switch to lockout | Activated safety chain | Vitodens 200 |
| 04, 05, 06, 08 | The controls switch to lockout | The speed of the fan is too high or low at the start | Vitodens 200 |
| 5A, B7, B8 | Control mode | Supply temperature sensor Lead break Low loss header | All Viessmann boilers |
| 5A, B7, B8 | Control mode Blocked burner | Broken cable sensor | All Viessmann boilers |
| 5C, 5D, 5E, 5F | Control mode | Communication fault | Vitotronic 300-K, 200 |
| 07, 09 | The controls switch to lockout | Whilst in standby mode the basic level of air pressure isn't correct | Vitodens 200 |
| 8C, 8D, 8E, 8F | Control mode | Communication fault | Vitocontrol-S Vitotronic 100, 200, 300-K |
| 10 | Operation based on the outdoor temperature of 0C | The outdoor temperature sensor has short circuited | Vitodens 200-W, 222-F Vitotronic 300-K, 300, 200, 200-H, 050/200-H Vitocontrol-S |
| 10 | Constant mode Outdoor temperature controls | The outdoor temperature sensor has shorted out | Vitotronic 300-K, MW2S with 100, WB2B with 100 Vitodens 100-W (combiPLUS) / 200-W Vitocontrol-S |
| 10, 14, F3, F4 | Burner control in lockout | No present flame signal | Vitodens 200 |
| 18, D1 | Operation based on the outdoor temperature of 0C Constant Mode | Sensor cable broken for outdoor tempearture | Vitodens 100, 200-W, 222-F Vitotronic 300-K with 100 Vitocontrol-S |
| 18, D1 | Operation based on the outdoor temperature of 0C | Outdoor temperature sensor has open circuit | Vitotronic 100, 200, 300, 050-200-H, 300-K, MW1 with 100 Vitocontrol-S |
| 18, D1 | Controls as if outdoor temperature | Outdoor temperature sensor or lead break | Vitotronic 200-H, 300-K, MW1B with 300 / 300-K, MW2B with 200 |
| 18, D1 | When outdoor temperature is 0C it activates | Cable break on the outdoor temperature sensor | Vitotronic 050/200-H |
| 18, D1 | Fault in burner | The DIP switch S2 is on | Vitodens 100-W |
| 19 | Operation based on the outdoor temperature of 0C | Wireless outdoor temperature sensor Fault with communication | Vitotronic 300 |
| 20 | Supply temperature may not be high enough Vitocontrol-S controls in a stand alone manner without supply temperature sensor | Temperature sensor has shorted out | Vitocontrol-S with Vitotronic 100 Vitotronic 200, 300-K |
| 20 | Low loss header Temperature sensor regulates without supply | System supply temperature sensor has short circuited | Vitodens 200-W, 222-F |
| 20 | Supply temperature may not be high enough There is no supply temperature sensor for the stand-alone control unit | The common supply temperature sensor has short circuited | Vitocontrol-S with Vitotronic 100 Vitotronic 100, 200, 300, 300-K |
| 20 | Supply temperature may not be high enough MW1S controls in a stand-alone manner without strap-on sensor | The strap-on temperature sensor has short circuited | Vitotronic 100, 300-K |
| 20 | Low loss header Temperature sensor regulates without supply | System flow temperature sensor has short circuited | Vitocrossal 300 |
| 20 | Mixing valve closed | Supply temperature sensor has short circuited Mixing valve circuit M1 | Vitotronic 050/200-H, 200, 200-H, 300 |
| 20 | Low loss header Temperature sensor regulates without supply | The system supply temperature sensor has shorted out | Vitodens 200-W |
| 21 | Return water temperature operation without influence | Return water temperature sensor short circuited | Vitotronic 200, 300 |
| 25 | There is a high boiler water temperature whilst the boiler is in operation | For 30 minutes or over the emissions test switch has turned to the hand symbol | Vitodens 200 |
| 26 | Continuous relay test when the boiler is in operation | For 30 minutes the setting mode for minimum or maximum rated input has been active | Vitodens 200 |
| 28 | Mixing valve is closed | Open circuit on the supply temperature sensor of the mixing valve circuit M1 | Vitotronic 050/200H |
| 28 | Low loss header Regulates without supply temperature sensor | Cable broken on the system supply temperature sensor | Vitocrossal 300 Vitodens 200-W, 222-F |
| 28 | Mixing valve closes | Cable broken on the supply temperature sensor | Vitotronic 050/200H |
| 28 | Stand-alone control unit without supply temperature sensor The temperature may not be high enough | Common supply temperature sensor, lead break | Vitotronic 300, 300-K |
| 28 | Vitotronic 300-K & MW1S controls in a stand alone manner without strap-on sensor The temperature may not be high enough | Strap-on temperature sensor has an open circuit | Vitotronic 100, 300-K |
| 28 | Vitocontrol-S & WB2B controls in a stand alone manner without supply temperature sensor The temperature may not be high enough | Cable broken on the common supply temperature sensor | Vitocontrol-S Vitotronic 100, 300-K |
| 28 | Vitocontrol-S, VD2, CT3, CM2 controls in a stand alone manner without temperature sensor The temperature may not be high enough | Common supply temperature sensor has an open circuit | Vitotronic 100 Vitocontrol-S |
| 28 | Mixing valve is in the process of being closed | Heating circuit with mixing valve M1 Lead break Supply temperature sensor | Vitotronic 200, 200-H, 300 |
| 29, 41, 49, F80, F81, F83, F88 and F89 | No influence of return water temperature and normal operation | Return water temperature sensor has an open circuit 1 or 2 | Vitotronic 200, 300 |
| 30 | The burner is started and stopped via adjustable high limit | Water temperature sensor has short circuited | Vitocontrol-S Vitoronic 100, 200, 300 Vitodens 200-W, 222-F Vitocrossal 300 |
| 30 | Blocked burner | The water temperature sensor shorted out | Vitocontrol-S Vitotronic 100 Vitodens 100-W (CombiPLUS), 200-1 |
| 35 | The boiler doesn't activate | The reset button has been pressed, whilst the burner is off, but the emissions test switch is turned to the hand symbol | Vitodens 200 |
| 38 | Blocked burner | Water temperature sensor lead broken | Vitodens 100-W |
| 38 | Temperature controller starts and stops the burner | Water temperature sensor Lead break | Vitotronic 300-K, 300 |
| 38 | Blocked burner | Cable broken on water temperature sensor | Vitodens 200-W, 222-F, CombiPLUS |
| 38 | Burner switched on and off by the adjustable high limit | Temperature sensor has an open circuit | Vitotronic 100, 200, 300 Vitocontrol-S |
| 40, 44 | Mixing valve closes | Heating circuit 2 with mixing valve supply short circuit on temperature sensor | All Viessmann boilers |
| 48, 4C | Mixing valve is closing or has closed | Cable broken on mixing valve supply temperature sensor, it has an open circuit (Heating circuit 2) | All Viessmann boilers |
| 50, 51, 58, 59 | Fault with DHW No DHW heating | DHW tank temperature sensor or lead break has short circuited or an open circuit | Vitodens 200-W, 222-F |
| 52 | Control mode | Low loss header with temperature sensor supply which has short circuited | Vitotronic 300 |
| 52 | Blocked burner | Shorted out flow sensor | Vitodens 100-W CombiPLUS |
| 55, 56, 57 | Control mode | Maintenance or error | Vitotronic 300-K, 200 |
| 60, 68, 70, 78, BD, BE, BF | No output reduction Open return control Maximum temperature | Temperature sensor has short circuited or an open circuit | All Viessmann boilers |
| 80, 81, 82, 83, FD | Fault state in burner control unit System cools down Burner control unit locked out | Water temperature sensor or burner control unit has short circuited | All Viessmann boilers |
| 88, 89, E6 | Fault state with the burner control unit | Burner control unit Water temperature sensor Lead break | Vitotronic 300 |
| 90, 91, 92, 93, 94, 98, 99, 9A, 9B , 9C, 9E, 9F, AB | Control mode | Temperature sensor has short circuited | All Viessmann boilers |
| A0, A1, A2, AA, AC | The boiler cools down | Fault with the safety equipment at X2, X3, X7 of plugin adaptor 2 | Vitotronic 300, 300-K |
| A0, A1, A2, AA, AC | BUS fault: Boiler operates in emergency mode or the boiler cools down | BUS fault or open circuit on internal BUS connection | Vitodens 200 |
| A2 | N/A | Fault with the KM-BUS | Vitodens 200 |
| A3, B0, F1, FE1, FE2 | Blocked burner | Check flue gas temperature centre, it may not be properly positioned | All Viessmann boilers |
| A4 | Maximum speed reached for pump | Open circuit in BUS connection with variable speed heating circuit pump | Vitodens 200 |
| A5 | N/A | Short or open circuit | Vitodens 200 |
| A7 | Factory default control mode | Programming unit faulty | Vitocrossal 300 Vitodens 200-W, 222-F, 300 |
| A8 | Blocked burner, automatically started venting program | Minimum flow rate has not been achieved or air lock in internal circulation pump | Vitodens 222-F |
| A9, BA, BB, BC, FE0 | Control mode | Communication error | All Viessmann boilers |
| AD | Control mode | Configuration error with isolation valve (OC:2, OC:3, OC:4 set), (4E:1 not set) | Vitocontrol-S Vitotronic 100, 300, 300-K |
| B1 | Control mode | Communication error with programming unit | All Viessmann boilers |
| B2 | Boiler cools down | Sensor inputs are not being read correctly | Vitodens 200 |
| B3, E5 | Not possible to set via service level | Internal fault, data points not stored (VR20) | Vitodens 200 |
| B4 | Control characteristics undefined | Fault with internal electronics | Vitotronic 050/200-H |
| B4 | Regulates as if outside temperature was at 0C | Fault interally | Vitocontrol-S Vitotronic 100 Vitodens 200-W |
| B4 | Emissions test mode | Fault with internal electronics | Vitocontrol-S Vitotronic 100, 200, 300, 300-K |
| B5 | Control mode | Fault with internal electronics | All Viessmann boilers |
| B6 | Constant mode | Recognisation of invalid hardware | All Viessmann boilers |
| B9, ED, F0, FE5, FEC, FED, FEE, FEF, FFD, FFF | Fault of boiler control unit Normal operation | Fault interally | All Viessmann boilers |
| C1 | Control mode | External safety equipment | All Viessmann boilers |
| C2-C8, CD-CF, D2-D8, DA-DF, E0 | Control mode | Open circuit on KM BUS to solar control unit AM1 Extension DE-DE3 M1 Communication fault | All Viessmann boilers |
| C9, CA, CB | Boiler cools down | Maximum pressure limited error | Vitocontrol-S Vitotronic 100, 300, 300-K |
| CC, F0 | Large voltage fluctuations means the burner control unit switches to lockout | Differential air pressure sensor or open circuit | Vitodens 200 |
| D4 | Boiler cools down | Fuse F2 has blown or fixed high limit has responded | All Viessmann boilers |
| D5 | Boiler drives up to electronic maximum limit | The boiler is not logging in at the cascade control unit | All Viessmann boilers |
| E1, E7, E8, E9, EA, EB, EC, FF2 | Fault mode in relation to burner | During calibration ionization is too high | All Viessmann boilers |
| E2, E3 | Fault mode in relation to burner | Water flow rate too low during calibration Flow switch has caused shutdown | Vitodens 200-W, 222-F Vitotronic 300 |
| E4 | Blocked burner | Voltage supply faulty (24V) | All Viessmann boilers |
| EE, EF | Fault mode in relation to burner | When the burner starts the flame signal is too weak or missing | Vitocontrol-S Vitotronic 100, 300 Vitodens 200-W, 222-F Vitocrossal 300 |
| F5 | Blocked burner | Air pressure switch faulty | Vitodens 100-W, 200, 300 Vitotronic 300 |
| F6, 58, F9, FE1, FE2, FF6 | Gas pressure switch is showing there is no gas pressure or electrical connection fault | Gas valve shut off Faulty gas pressure switch Multiple issues with gas supply | All Viessmann boilers |
| FA, FB | Fault mode in relation to burner Emergency operation | Plug-in connection Fan not at standstill | All Viessmann boilers |
| FB7, FF4, FF2, FF7, FF8, FF9 | Fault state with furner control unit, system cools down, lockout of burner control unit Type of coding card | Coding card not correctly inserted into burner control unit, or faulty card Coding card doesn't match burner control unit | Vitocrossal 200 |
| FC | Fault mode in relation to burner | Faulty gas valve Faulty modulation valve control Vent system blocked | All Viessmann boilers |
| FE | Fault mode in relation to burner | Faulty main printed circuit board Strong interference field nearby | All Viessmann boilers |
| FE4 | Burner has shut down | Under set voltage detected multiple times | Vitocrossal 200 |
| FFA, FFB, FR | Fault mode in relation to burner Fan runs without demand | Fan has not stopped Faulty 100A cable Faulty fan Fault with burner control unit | Vitocrossal 200, 400-620, 186-311 |