BoilerFaultCodes F.035 Emergency
Boiler Fault Code F.035
Also written as F035 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F.035 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 because the pipe that vents exhaust gases outside or brings in fresh air is blocked or obstructed. (As reported on Vaillant ecoTEC Plus 836)
Pick your boiler brand for the F.035 fix
Source
Information for the F.035 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