BoilerFaultCodes F1 or F4 High
Boiler Fault Code F1 or F4
Also written as F1ORF4 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F1 or F4 appears across 1 boiler brand and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is failing to light the internal flame needed to produce heat and hot water despite several attempts. (As reported on Saunier Duval Semia Condens F30 E)
Pick your boiler brand for the F1 or F4 fix
Source
Information for the F1 or F4 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 27 April 2026