Boiler Fault Code Red LED is 'ON'

Also written as REDLEDISON — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026

Fault code Red LED is 'ON' 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 has detected an internal electrical or safety fault and has stopped running to prevent damage. (As reported on Potterton Kingfisher MF RSL)