Boiler Fault Code F-

Also written as F — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026

Fault code F- 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 has stopped working because it has detected a specific internal problem, which it will show by alternating the 'F' with another number or letter. (As reported on Ideal Isar System)