BoilerFaultCodes Mains light Low
Boiler Fault Code Mains light
Also written as MAINSLIGHT — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Mains light appears across 1 boiler brand and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is receiving power as normal and this light simply confirms it is switched on, not indicating a fault. (As reported on Potterton Promax)
Pick your boiler brand for the Mains light fix
Source
Information for the Mains light 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