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Vaillant boiler error codes

Combining British manufacturing with German engineering, Vaillant’s award-winning combination, system and open vent boilers are renowned for their reliability, performance and efficiency.

Occasionally some things can go wrong, that’s why we’ve created our handy at-a-glance table of Vaillant error codes below and our guide to Common Vaillant Boiler Problems and Repair Advice.

Should you need professional help with your broken boiler, then simply use one of our enquiry forms and we will connect you with the best heating engineers local to you.

Vaillant EcoTEC 65kW Error Codes

Listed below are the most common error codes that you might see on your Vaillant EcoTEC 65kW boiler.

Fault CodePossible Cause
S.0Heating issue, no heat demand
S.1Fan start-up error
S.2Pump flow error
S.3Heating mode error – ignition problem
S.4Heat mode – burner on error
S.6Heating mode – fan overrun error
S.7Heating mode – pump overrun error
S.8Heating remaining cut off for XX amount of time
S.31No heat demand summer operating mode
S.34Heating mode frost protection error
S.20Hot water requirement error
S.22Hot water handling pump flow error
S.24Hot water operation burner is on
S.85Service message quantity of circulation water

Vaillant ecoTec Pro

Listed below are the most common error codes that you might see on your Vaillant EcoTec Pro boiler.

Fault CodePossible Cause
F.00 / F.0Flow temperature sensor interruption
F.01 / F.1Return temperature sensor interruption
F.10Flow NTC short circuit
F.11Return NTC short circuit
F.20Safety switch off temperature limiter
F.22Safety switch off low water pressure
F.23Safety switch off temperature difference too great
F.24Safety switch off temperature is rising too fast
F.25Safety switch off flue gas temperature too high
F.26Error with gas valve – possible no function
F.27Safety switch off flame simulation
F.28Failure during start up – ignition unsuccessful to start
F.29Failure during operation – re-ignition unsuccessful
F.32Fan error
F.49eBUS error – possible short circuit
F.61Error with gas valve regulation
F.62Error with gas valve – switch off delay
F.11EEPROM error
F.20Electronics / NTC error
F.22Electronic temperature error could be overheating due to external influences
F.23Heating mode – pump overrun error
F.24Heating remaining cut off for XX amount of time
F.25No heat demand summer operating mode
F.26Heating mode frost protection error
F.27Hot water requirement error
F.28Hot water handling pump flow error
F.29Hot water operation burner is on
F.32Service message quantity of circulation water