L5 High

Boiler Fault Code L5

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code L5 appears across 3 boiler brands and 27 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has stopped working because a sensor that monitors the temperature of the water coming back into the unit has detected a problem or failed. (As reported on Ideal Logic Code Combi ESP1)

Pick your boiler brand for the L5 fix

Baxi L5 1 model Ideal L5 18 models Keston L5 8 models

Source

Information for the L5 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