BoilerFaultCodes LLLLL ::::: FFFFF High
Boiler Fault Code LLLLL ::::: FFFFF
Also written as LLLLLFFFFF — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code LLLLL ::::: FFFFF 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 is failing to light the flame properly after three attempts, meaning it currently cannot provide heating or hot water. (As reported on Ideal Isar HE)
Pick your boiler brand for the LLLLL ::::: FFFFF fix
Source
Information for the LLLLL ::::: FFFFF 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