BoilerFaultCodes L5 or F5 High
Boiler Fault Code L5 or F5
Also written as L5ORF5 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code L5 or F5 appears across 1 boiler brand and 8 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 returning from your radiators, preventing it from heating correctly. (As reported on Ideal Esprit)
Pick your boiler brand for the L5 or F5 fix
Source
Information for the L5 or F5 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