F1 High

Boiler Fault Code F1

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code F1 appears across 15 boiler brands and 111 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has shut down because it detected that the exhaust gases have become too hot, which is a safety feature to prevent damage or dangerous operation. (As reported on Viessmann Vitodens 333-F)

Pick your boiler brand for the F1 fix

Atag F1 5 models Ferroli F1 1 model Glow-worm F1 24 models Heatline F1 7 models Ideal F1 23 models Ikon F1 1 model Keston F1 2 models Pro F1 3 models Protherm F1 2 models Ravenheat F1 6 models Saunier Duval F1 6 models Vaillant F1 2 models Viessmann F1 17 models Worcester Bosch F1 11 models Zanussi F1 1 model

Source

Information for the F1 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 31 August 2026