Viessmann Boiler Fault Codes List

When your Viessmann boiler encounters an issue, the boiler will lockout and cease to function as a safety precaution. The boiler will then display an error code/fault code on the LCD display on the front of the boiler to help you identify what has caused the issue.

This error code list is to help you identify the problem with your Viessmann boiler, we don’t advise you to try and fix your boiler yourself. This error code list is a guide to help you identify the issue with your Viessmann boiler. Only a Gas Safe registered engineer should attempt to fix your boiler.

If your boiler isn’t working but it isn’t displaying a fault code either then check your water, gas, and electricity supplies to ensure there is no issue with supply. If you have a prepay meter, make sure you have credit. Check your property has running water from the cold taps, that your gas is working by lighting the hob or gas fire and that your electricity is working by turning on a light.

Your boiler may be on a separate circuit, so if the rest of your home has electricity but the LCD display on your boiler isn’t displaying anything your boiler may not be receiving power and you may need to call an electrician or Gas Safe engineer. To know more about the parts that make a combi boiler, check out our blog.

If you’re reading this blog thinking ‘it will be easier to buy a new boiler’, then why not complete our online survey, which helps you get a boiler quote in only 90-seconds. To help you choose your new boiler, we have a Boiler Comparison tool that allows you to compare up to three boiler models or brands at one time, to help you find the best new boiler for your home.

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Viessmann Fault Code 5C, 5D, 5E and 5F

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

Viessmann Fault Code 10

Boiler model	Boiler fault	Diagnosis
Vitodens 200-W / 222-F / Vitotronic 300 / 200/ 200-H / 050/200-H / 300-K / vitocontrol-S	The boiler operates based on an 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	The outdoor temperature sensor shorted out

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

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

Viessmann Fault Code D4

Boiler model	Boiler fault	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

Viessmann Fault Code 18 and D1

Boiler model	Boiler fault	Diagnosis
Vitodens 100 / 200-W / 222-F / Vitotronic 300-K With 100 / Vitocontrol-S	The boiler operates based on the 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”

Viessmann Fault Code A4

Boiler model	Boiler fault	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

Viessmann Fault Code 0C

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

Viessmann Fault Code C1

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

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

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

Viessmann Fault Code 41

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

Viessmann Fault Code 88, 89, and E6

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

Viessmann Fault Code AD

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

Viessmann Fault Code F5

Boiler model	Boiler fault	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

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

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

Viessmann Fault Code B4

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

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

Boiler model	Boiler fault	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

Viessmann Fault Code B5

Boiler model	Boiler fault	Diagnosis
All Viessmann boilers	Control Mode	External safety equipment

Viessmann Fault Code 19

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

Viessmann Fault Code B2

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

Viessmann Fault Code 21

Boiler model	Boiler fault	Diagnosis
Vitotronic 200 / 300	operation without influence of return water temperature	Short circuit – Return water temperature sensor

Viessmann Fault Code 0b

Boiler model	Boiler fault	Diagnosis
Vitodens 200	The burner control switches to lockout. The fan does not idle 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)

Viessmann Fault Code FE

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

Viessmann Fault Code 20

Boiler model	Boiler fault	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

Viessmann Fault Code 55, 56 and 57

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

Viessmann Fault Code EE and EF

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

Viessmann Fault Code FC

Boiler model	Boiler fault	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

Viessmann Fault Code FE4

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

Viessmann Fault Code 10, 14, F3, and F4

Boiler model	Boiler fault	Diagnosis
Vitodens 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.

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

Boiler model	Boiler fault	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.

Viessmann Fault Code 50, 51, 58 and 59

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

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

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

Viessmann Fault Code 48 and 4C

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

Viessmann Fault Code 40 and 44

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

Viessmann Fault Code E2 and E3

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

Viessmann Fault Code F-FA, F-FB and FR

Boiler model	Boiler fault	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

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

Boiler model	Boiler fault	Diagnosis
All Viessmann boilers	– No output reduction – Return control open – Boiler with maximum temperature	Short/open circuit – Temperature sensor [17A]

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

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

Viessmann Fault Code D5

Boiler model	Boiler fault	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.

Viessmann Fault Code B6

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

Viessmann Fault Code CC and F0

Boiler model	Boiler fault	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

Viessmann Fault Code 52

Boiler model	Boiler fault	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)

Viessmann Fault Code 5A, B7, and B8

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

Viessmann Fault Code 38

Boiler model	Boiler fault	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

Viessmann Fault Code A7

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

Viessmann Fault Code C9, CA and CB

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

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

Boiler model	Boiler fault	Diagnosis
All Viessmann boilers	Control mode	Short circuit – Temperature sensor

Viessmann Fault Code 0F

Boiler model	Boiler fault	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

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

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

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

Boiler model	Boiler fault	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)

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

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

Viessmann Fault Code 28

Boiler model	Boiler fault	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 / 22-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

Viessmann Fault Code B1

Boiler model	Boiler fault	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 200 / 300	Normal operation	Service required
Vitotronic 050/200-H	Undefined control characteristics	Internal electronics fault

Viessmann Fault Code E4

Boiler model	Boiler fault	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

Viessmann Fault Code A8

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

Viessmann Fault Code FA and FB

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

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

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

Viessmann Fault Code B3 and E5

Boiler model	Boiler fault	Diagnosis
All Viessmann boilers	Constant mode	Invalid hardware recognised

Viessmann Fault Code 30

Boiler model	Boiler fault	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 / Vitodens 100-W (CombiPLUS)/ 200-1	Burner blocked	Boiler water temperature sensor shorted out

Viessmann Boiler Manuals

Is it time to get a new boiler?

At some point, your boiler might stop heating your home as it used to, despite its regular yearly service.

If you’ve noticed that your heating experience has changed, i.e. your radiators are taking longer to heat up, or your boiler is losing pressure regularly (more than usual), it might be time to invest in a new boiler.

But before you commit to the big purchase, ask a heating engineer to check that there isn’t a build-up in your heating system preventing your boiler from working as it should.

However, If your boiler keeps breaking down, it may be cheaper, in the long run, to cut your losses and get a new one, just come to us at WarmZilla and we’ll sort you out!

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Why should you buy a new boiler from WarmZilla?

When you purchase a new or replacement boiler with WarmZilla, your boiler package will also include;

Your chosen boiler, along with the necessary flue kit needed for your central heating system
Installation by a qualified Gas Safe Engineer
Removal of your old boiler and parts
A FREE system cleanse of your central heating system
Chemical Inhibitor for added protection for your new boiler
10-years guarantee, which will be registered by WarmZilla after installation
A FREE magnetic system filter for ongoing protection
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