BoilerFaultCodes F05 L05 High
Boiler Fault Code F05 L05
Also written as F05L05 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F05 L05 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 detected a problem with the sensor that monitors the temperature of the water coming back from your radiators, preventing it from heating up correctly. (As reported on Ideal Logic Code Combi ESP1)
Pick your boiler brand for the F05 L05 fix
Source
Information for the F05 L05 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