Last updated on: 29 August 2024

Viessmann Boiler Fault Codes: A Comprehensive List and Common Issues

Viessmann boiler fault codes serve as a valuable tool for skilled technicians to detect and troubleshoot issues with Viessmann boilers. These codes utilise a combination of letters and numbers to pinpoint specific problems within the system, such as overheating, malfunctioning pumps, or low water pressure.

This article will provide a comprehensive list of Viessmann boiler codes and delve into one or two common fault codes in greater detail. By familiarising yourself with these codes, you can quickly identify and resolve any issues with your Viessmann boiler, ensuring optimal performance and longevity.

Company Overview

Viessmann is a leading manufacturer of high-efficiency boilers and heating products globally. The company prides itself on providing reliable and sustainable heating solutions for commercial and residential applications. Viessmann has a wide range of boilers, including gas-fired condensing and oil-fired boilers, designed to be energy-efficient while meeting the highest emissions standards.

In addition, Viessmann offers an array of smart controls to provide users with easy management of their heating systems while minimising energy consumption, reducing fuel costs, and promoting environmental sustainability. Combining modern technologies such as digital communications with traditional engineering techniques, Viessman’s innovative solutions have gained recognition from professionals worldwide as the ideal choice for customers looking for top-quality equipment with lower operational costs.

List of Viessman boiler fault codes, problems, and the reasons behind them

Vitoden 200 Boiler Error Codes

Fault CodeProblemReason
02Burner control switches to lockoutSafety chain was activated
04, 05, 06, 08Burner control switches to lockoutFan speed too high/low at start
07, 09Burner control switches to lockoutBasic level of air pressure threshold in standby mode does not correct
0DBurner control switches to lockoutReset button pressed repeatedly or while burner is running
1A, 1BBurner blockedFlow sensor 1, 2 faulty
1FBurner blockedDifferential flow rate too large
25Boiler operates with high boiler water temperatureEmissions test switch turned to “hand symbol” for 30 minutes already
26Boiler operates with continuous relay testSetting mode for maximum or minimum rated input active for 30 minutes already
35Boiler does not activateReset button (pressed while burner is OFF) with emissions test switch turned to “hand symbol”
A2N/AKM-BUS fault to Vitocom
A5N/AShort circuit / open circuit

Viessmann Fault Code 0B

ModelProblemReason
Vitodens 200Burner control switches to lockout. Fan does not idle after auto reset (incorrect fan rpm).Severe wind conditions in vent system.
Vitodens 100-WBurner blockedInsufficient water flow, incorrect flow direction, defective flow switch.

Viessmann Fault Code 0C

ModelProblemReason
Vitodens 100-WBurner blockedInsufficient power supply
Vitodens 200Burner control switches to lockoutFlame signal still present after switching off

Viessmann Fault Code 0F

ModelProblemReason
Vitodens 222-FControl modeCode “0F” is only displayed in the fault history
Vitotronic 300 / Vitotronic 300-K, with Vitotronic 300 / Vitodens 200-W / Vitocontrol-S, with Vitotronic 100Control mode / Controlled operationBoiler service required
Vitotronic 200 / 300Normal operationBoiler service required
Vitocontrol-S, MW1 with Vitotronic 100 / Vitotronic 300-K, MW1S with Vitotronic 100Control modeMaintenance – “0F” is only displayed in the fault history

Viessmann Fault Code 10

ModelProblemReason
Vitodens 200-W / 222-F / Vitotronic 300 / 200/ 200-H / 050/200-H / 300-K / Vitocontrol-SBoiler operates based on outdoor temperature of 32°F / 0°CShort circuit – outdoor temperature sensor
Vitotronic 300-K, MW2S with Vitotronic 100 / Vitodens 100-W (combiPLUS) / 200-w / Vitocontrol-S, WB2B with Vitotronic 100Controls as if the outdoor temperature / Constant ModeOutdoor temperature sensor shorted out

Viessmann Error Code 10, 14, F3, and F4

ModelProblemReason
Vitodens 200-W / 222-F / Vitotronic 300 / 200 / 200-H / 050/200-H / 300-K / Vitocontrol-SBoiler operates based on outdoor temperature of 32°FShort circuit – outdoor temperature sensor
Vitotronic 300-K, MW2S with Vitotronic 100 / Vitodens 100-W (combiPLUS) / 200-w / Vitocontrol-S, WB2B with Vitotronic 100Control as if the outdoor temperature is in constant modeOutdoor temperature sensor shorted out

Viessmann Fault Code 18 and D1

ModelProblemReason
Vitodens 100 / 200-W / 222-F / Vitotronic 300-K With 100 / Vitocontrol-SBoiler operates based on outdoor temperature of 32°F / 0°C / Constant ModeOutdoor temperature sensor cable broken
Vitotronic / 100 / 200 / 300 / 050/200-H / 300-K / Vitocontrol-S, MW1 with Vitotronic 100Operates on basis of 32°F / 0°C outdoor temperatureOpen circuit – Outdoor temperature sensor
Vitotronic 200-H / Vitotronic 300-K, MW1B with Vitotronic 300 / Vitotronic 300-K, MW2B with Vitotronic 200Controls as if the outdoor temperatureLead break – Outdoor temperature sensor
Vitotronic 050/200-HActivates after 0°C / 32°F outdoor temperatureCable break – Outdoor temperature sensor
Vitodens 100-WBurner in fault modeDIP switch S2 is set to “ON”

Viessmann Fault Code 19

ModelProblemReason
Vitotronic 300Activates after 0°C / 32°F outdoor temperatureCommunication fault, wireless outdoor temperature sensor

Viessmann Fault Code 20

ModelProblemReason
Vitocontrol-S with Vitotronic 100 / Vitotronic 300 / 300-K / 200 / 100Stand-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 200Vitocontrol-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 300Regulates without supply temperature sensor (low-loss header)Short circuit – System Flow temperature sensor
Vitodens 200-W / 222-FRegulates without supply temperature sensor (low-loss header)Short circuit – System supply temperature sensor
Vitotronic 050/200-H / 200 / 200-H / 300Mixing valve closedShort circuit – Supply temperature sensor / mixing valve circuit M1
Vitotronic 300-K, with Vitotronic 100Vitotronic 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-WRegulates without supply temperature sensor (low-loss header)System supply temperature sensor shorted out

Viessmann Fault Code 21

ModelProblemReason
Vitotronic 200 / 300Operation without influence of return water temperatureShort circuit – Return water temperature sensor

Viessmann Error Code 28

ModelProblemReason
Vitocontrol-S with Vitotronic 100Vitocontrol-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 100Vitocontrol-S, WB2B controls in a stand-alone manner w/o supply temperature sensor (supply temperature might not be high enough)Common supply temperature sensor cable broken
Vitocrossal 300 / Vitodens 200-W / 22-FRegulates without supply temperature sensor (low-loss header)System supply temperature sensor cable broken
Vitotronic 050/200-HMixing valve closesCable break – Supply temperature sensor
Vitotronic 050/200-HMixing valve is closedOpen circuit – Supply temperature sensor of mixing valve circuit M1
Vitotronic 200-H / Vitotronic 200 / 300Mixing valve is being closedLead break – Supply temperature sensor in heating circuit with mixing valve M1 (heating circuit 1)
Vitotronic 300 Vitotronic / 300-K with Vitotronic 300 / 200Stand-alone control unit without supply temperature sensor (possibly supply temperature not high enough)Lead break, common supply temperature sensor
Vitotronic 300-K with Vitotronic 100Vitotronic 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

Viessmann Fault Code 29, 41, 49, F80, F81, F83, F88 and F89

ModelProblemReason
Vitotronic 200 / 300Normal operation without influence of return water temperatureOpen circuit 1 or 2 – Return water temperature sensor (of mixing valve circuit 1)

Viessmann Fault Code 30

ModelProblemReason
Vitocontrol-S, with Vitotronic 100 / Vitocrossal 300 / Vitodens 200-W / 222-F / Vitotronic 100 / 200 / 300Adjustable high limit burner is started and stoppedShort circuit – Boiler water temperature sensor
Vitocontrol-S with Vitotronic 100 / Vitodens 100-W (CombiPLUS)/ 200-1Burner blockedBoiler water temperature sensor shorted out

Viessmann Fault Code 38

ModelProblemReason
Vitodens – 200-W / 222-F / COMBIPLUSBurner blockedBoiler water temperature sensor cable broken
Vitotronic 100 / 200 / 300 / Vitocontrol-S with Vitotronic 100Burner is switched on and off by the adjustable high limitOpen circuit – Boiler temperature sensor
Vitotronic 300-K with Vitotronic 300 / Vitotronic 300-K with Vitotronic 300The burner is started and stopped via a temperature controllerLead break, boiler water temperature sensor
Vitodens 100-WBurner blockedBoiler water temperature sensor lead broken

Viessmann Error Code 40 and 44

ModelProblemReason
All Viessmann boilersMixing valve closedHeating circuit 2 with mixing valve supply short circuit on temperature sensor

Viessmann Fault Code 41

ModelProblemReason
Vitotronic 300Operation without accounting for return water temperatureShort circuit – Return water temperature sensor of mixing valve circuit 2

Viessmann Fault Code 48 and 4C

ModelProblemReason
All Viessmann boilersMixing valve closes / closedHeating circuit 2 with mixing valve supply temperature sensor cable broken / open circuit

Viessmann Fault Code 50, 51, 58 and 59

ModelProblemReason
Vitodens 200-W / 222-FNo DHW heating / Fault with DHWShort circuit/open circuit – DHW tank temperature sensor or lead break

Viessmann Error Code 52

ModelProblemReason
Vitotronic 300Control modeShort circuit – Supply temperature sensor low-loss header
Vitodens 100-W CombiPLUSBurner blocked (with CombiPLUS only)Flow sensor shorted out (in CombiPLUS)

Viessmann Fault Codes 55, 56, and 57

ModelProblemReason
Vitotronic 300-K, with Vitotronic 200Control modeMaintenance or error on Vitotronic 100 of boiler 5-8

Viessmann Fault Codes 5A, B7, and B8

ModelProblemReason
All Viessmann boilersControl modeLead break, low-loss header – Supply temperature sensor
All Viessmann boilersBurner blocked / control modeSensor cable broken

Viessmann Error Codes 5C, 5D, 5E, and 5F

ModelProblemReason
Vitotronic 300-K with Vitotronic 200Control modeCommunication fault, Vitotronic 100 of boiler 5-8

Viessmann Fault Codes 60, 68, 70, 78, BD, BE, and BF

ModelProblemReason
All Viessmann boilersNo output reductionReturn control open, boiler with maximum temperature and Short/open circuit – Temperature sensor [17A]

Viessmann Fault Codes FD, 80, 81, 82, and 83

ModelProblemReason
All Viessmann boilersBurner control unit in a fault state; system cools down; burner control unit locked outShort circuit – Boiler water temperature sensor, burner control unit

Viessmann Error Codes 88, 89, and E6

ModelProblemReason
Vitocontrol-S with Vitotronic 100 / Vitotronic 300-K with Vitotronic 100 / 200Control modeCommunication error

Viessmann Fault Codes 8C, 8D, 8E, and 8F

ModelProblemReason
Vitotronic 300Burner control unit in an error modeLead break, boiler water temperature sensor, burner control unit

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

ModelProblemReason
Viessmann boilersControl modeShort circuit – Temperature sensor [5] / [6] / [7] / [10]

Viessmann Error Codes A0, A1, A2, AA, and AC

ModelProblemReason
Vitodens 200Pump running at maximum speedOpen circuit – Internal BUS connection issue

Viessmann Fault Codes F1, A3, B0, FE1, and FE2

ModelProblemReason
Vitocrossal 300 / Vitodens 200-W / 222-F / 300Control mode is in factory default settingProgramming unit is faulty

Viessmann Fault Code A4

ModelProblemReason
Vitodens 222-FBurner blocked. The venting program automatically starts.Airlock in the internal circulation pump or minimum flow rate not achieved

Viessmann Fault Code A7

ModelProblemReason
Vitocontrol-S with Vitotronic 100 / Vitotronic 100 / Vitotronic 300-K with Vitotronic 300Control mode (stays in factory default setting)Isolation valve error coding OC:2, OC:3, or OC:4 set, and coding 4E:1 not set

Viessmann Error Code A8

ModelProblemReason
All BoilersControl mode issueProgramming unit communication fault

Viessmann Fault Codes A9, BA, BB, BC, and FE0

ModelProblemReason
Vitodens 200Boiler cools downSensor inputs are not read correctly
Viessmann Fault Code AD
ModelProblemReason
Vitodens 200Setting via service level not possibleData points are not stored internal error VR20

Viessmann Fault Code B1

ModelProblemReason
Vitocontrol-S with Vitotronic 100 / Vitotronic 100 / 200 / 300 / Vitotronic 300-K with Vitotronic 100Test mode on emissionsInternal electronics error
Vitocontrol-S with Vitotronic 100 / Vitodens 200-WRegulates as if the outside temperature was 32°FInternal error
Vitotronic 050/200-HControl characteristics undefinedElectronics internal error

Viessmann Error Code B2

ModelProblemReason
All Viessmann boilersControl modeInternal electronics error
Viessmann Fault Codes B3 and E5
ModelProblemReason
All boilersConstant ModeInvalid hardware recognized

Viessmann Fault Code B4

ModelProblemReason
Vitocontrol-S with Vitotronic 100 / Vitotronic 100 / 200 / 300 / Vitotronic 300-K with Vitotronic 100Emissions test modeInternal electronics fault
Vitocontrol-S with Vitotronic 100 / Vitodens 200-WRegulates as if the outside temperature was 32°F (0°C)Internal fault
Vitotronic 050/200-HUndefined control characteristicsInternal electronics fault

Viessmann Fault Code B6

ModelProblemReason
All Viessmann boilersControl modeOpen circuit – KM bus to solar control unit communication error

Viessmann Fault Codes B9, ED, F0, FE5, FEC, FED, FEE, FEF, FFD, and FFF

ModelProblemReason
Vitocontrol-S with Vitotronic 100 / Vitotronic 100 / 300 / Vitotronic 300-K with Vitotronic 300Boiler cools downError maximum pressure limiter 1 2

Viessmann Fault Code C1

ModelProblemReason
All Viessmann boilersBurner control unit switches to lockout, this could be due to large line voltage fluctuationsDifferential air pressure sensor open circuit

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

ModelProblemReason
All Viessmann boilersBoiler cools downFixed high limit has responded or fuse F2 has blown.

Viessmann Error code C9, CA, and CB

ModelProblemReason
All Viessmann boilersBoiler drives up to electronic maximum limitBoiler does not log in at the cascade control unit

Viessmann Error code CC and F0

ModelProblemReason
All Viessmann boilersBurner control unit is in fault modeIonisation current too high during calibration – Boiler temperature limiter responded air or blockage in system/pump error

Viessmann Fault Code D4

ModelProblemReason
Vitotronic 300 / Vitotronic 300-K with Vitotronic 300Boiler cools downError with safety equipment at ‘X2/X3/X7’ of plug-in adaptor 2 for external safety equipment
Vitodens 200Boiler is operating in emergency mode (after 30 mins BUS error) or boiler cools downInternal bus error or open circuit internal bus connection

Viessmann Fault Code D5

ModelProblemReason
All Viessmann boilersBurner blockedFlue gas temperature sensor not properly positioned – Check Sensor External pump fitted on system

Viessmann Fault Codes FF, E1, E7, E8, E9, EA, EB, EC, and FF2

ModelProblemReason
Vitodens 200-W / 222-F / Vitotronic 300Burner in fault modeFlow rate for heating hot water is too low during calibration / flow switch caused shutdown

Viessmann Error Code E2 and E3

ModelProblemReason
All boilersBurner in fault modeHeating water flow rate too low during calibration; flow switch caused shutdown

Viessmann Fault Code E4

ModelProblemReason
Vitotronic 300, Vitodens 200-W, 222-F, Vitocrossal 300, Vitocontrol-S with Vitotronic 100Burner errorBurner starts flame signal is too weak or missing

Viessmann Fault Codes EE and EF

ModelProblemReason
Vitocontrol-S with Vitotronic 100 / Vitocrossal 300 / Vitodens 200-W / 222-F / Vitotronic 300Burner blockedFaulty air pressure – switch air damper flap is stuck

Viessmann Fault Code F5

ModelProblemReason
All Viessmann boilersGas pressure switch shows no gas pressure / electrical connection errorGas shut-off valve closed / gas pressure switch faulty / multiple problems with gas supply

Viessmann Fault Codes F6, 58, F9, FE1, FE2, and FF6

ModelProblemReason
All Viessmann boilersBurner in error mode emergency operationFan not at standstill / plug-in connection error

Viessmann Fault Codes FA and FB

ModelProblemReason
All Viessmann boilersControl modeCommunication Fault with boiler

Viessmann Error Codes FB7, FF4, FF2, FF7, FF8, and FF9

ModelProblemReason
Vitocrossal 200Case 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.

Viessmann Fault Code FC

ModelProblemReason
All Viessmann boilersBurner in fault modeGas valve faulty or faulty modulation valve control; or vent system blocked

Viessmann Error Code FE

ModelProblemReason
All Viessmann boilersBurner blocked or in error modeStrong interference (EMC) field nearby, or faulty main PCB

Viessmann Error Code FE4

ModelProblemReason
Vitocrossal 200Burner shuts downMultiple detection of undervoltage

Viessmann Fault Codes FFA, FFB, and FR

ModelProblemReason
Vitocrossal 200 / 400-620 / 186-311Fan runs without demand; burner control unit in a fault stateFan has not stopped; cable [100A] faulty; fan faulty; burner control unit faulty

Viessmann Error Code F4 EE

ModelProblemReason
ViessmannCondensate pipe has frozenAs the condensate pipe lies outside the house it can get freeze. You can thaw it yourself but contacting a gas safe engineer would be a more viable option.

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The 2 Most Common Viessman Boiler Fault Codes

02 Common Viessman Boiler Problems

After compiling a list of error and fault codes for Viessman boilers, it is important to address the two most prevalent issues troubling homeowners in the UK. These two common errors are the F2 fault code and the F4 fault code. To better understand these issues, let us delve into their details.

1. Viessman F2 fault code

The Viessmann boiler F2 fault code indicates a sudden interruption or lack of flame during the heating cycle. This type of issue could occur for various reasons, including gas valve issues, blocked flues, or dirty burner rods. The boiler system shuts down immediately as a safety precaution once this error occurs. Therefore, it requires immediate attention from a professional technician to accurately diagnose and fix the underlying cause of the problem.

Common Reasons behind the F2 fault code

There are three primary reasons for the f2 fault in Viessman boilers. Firstly, the condensate pipe can freeze during the cold winter because it is outside. This can disrupt the heating system. Secondly, heating sludge can also be a problem, as it can obstruct the heat flow in your home. Finally, airlocks and the loss of heating flame can also contribute to the F2 fault. It is important to address these issues promptly to ensure the proper functioning of your boiler.

How to fix F2 fault code

If the F2 fault code is occurring due to a frozen condensate pipe only, then the problem can be solved by unfreezing the pipe. If the fault is occurring due to other issues related to internal components, then you will have to contact a Gas Safe Engineer.

2. Viessman F4 fault code

The Viessmann F4 fault code is a commonly occurring issue in many heating systems. This code typically indicates a flame detection error, which means the unit is having trouble sensing the presence of a flame. There can be several reasons for this problem, including dirty or damaged electrodes, blocked burners or heat exchangers, faulty sensors or wiring, and gas supply or regulator issues.

It’s essential to address this issue immediately, as it could lead to safety hazards such as gas leaks and carbon monoxide buildup.

Common Reason behind the F4 fault code

Several common issues can cause the F4 fault code in Viessman boilers. One of the most frequent culprits is gas valves becoming stuck, which can prevent the boiler from igniting. Another potential problem is related to wiring or connection issues. Faulty or impaired flame sensors can also trigger the F4 error code.

Additionally, debris can block burner jets, preventing the boiler from igniting and leading to an F4 error. If none of these issues are the cause, the problem may lie with the PCB. In this case, it is best to have an engineer inspect the boiler and determine if the PCB needs to be replaced.

How to fix the F4 fault code

If you encounter an F4 fault code in your Viessmann boiler, you must seek the assistance of a Gas Safe Engineer. This issue indicates internal damage, which requires the expertise of a professional to address.

Fixing it yourself may result in further complications and potentially hazardous situations. Therefore, it is highly recommended that you leave this task in the capable hands of a qualified engineer.

Conclusion

Upon reading this article, you will no longer be caught off guard by any error codes that may appear on your Viessman Boiler. We have provided a detailed explanation of each code, so you know when to contact a Gas Safe Engineer.

However, if your boiler is becoming increasingly faulty and has surpassed the 10- to 15-year mark, it may be time to consider purchasing a new boiler. Our team is here to assist you in finding the perfect boiler to meet your needs.

Additionally, if budget constraints are a concern, we may be able to offer financing options. Don’t hesitate to contact us today for expert guidance and support.

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Get your new boiler and save your heating bill yearly with new energy efficient boiler.

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The information provided in this article has been collected from various sources. However, we suggest you consult a certified Gas-Safe Engineer in your area before making any decisions, as every individual’s home situation is unique.

Posted by: Martin Astley 12 July 2023