FL Medium

Boiler Fault Code FL

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code FL appears across 4 boiler brands and 4 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is displaying an error code for a feature that isn't actually used on this model, which usually indicates a simple electronic glitch or a programming error. (As reported on Ideal Logic Combi C24 C30 C35)

Pick your boiler brand for the FL fix

Biasi FL 1 model Ideal FL 1 model Johnson Starley FL 1 model Unical FL 1 model

Source

Information for the FL 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