FL Low

Boiler Fault Code FL

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code FL appears across 4 boiler brands and 7 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is accidentally trying to use a feature it doesn't have, which is usually caused by a minor electronic glitch or a recent settings change. (As reported on Ideal Logic Code Combi ESP1)

Pick your boiler brand for the FL fix

Biasi FL 1 model Ideal FL 4 models Johnson Starley FL 1 model Worcester Bosch 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 27 April 2026