BoilerFaultCodes F9, L9, F8 or L8 High
Boiler Fault Code F9, L9, F8 or L8
Also written as F9L9F8ORL8 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F9, L9, F8 or L8 appears across 1 boiler brand 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's internal computer has either lost its settings or suffered an electrical failure, meaning the system cannot communicate with itself to start up. (As reported on Ideal Concorde)
Pick your boiler brand for the F9, L9, F8 or L8 fix
Source
Information for the F9, L9, F8 or L8 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