M Unknown

Boiler Fault Code M

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

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

Pick your boiler brand for the M fix

Ariston M 1 model Main M 1 model Potterton M 1 model

Source

Information for the M 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 31 August 2026