BoilerFaultCodes F.040 Emergency
Boiler Fault Code F.040
Also written as F040 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F.040 appears across 1 boiler brand and 3 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is struggling to breathe properly because exhaust fumes are getting trapped or recycled back into the system instead of venting outside safely. (As reported on Vaillant ecoTEC Plus 832)
Pick your boiler brand for the F.040 fix
Source
Information for the F.040 fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026