Boiler Fault Code Red LED illuminated (Overheat)

Also written as REDLEDILLUMINATEDOVERHEAT — same fault.

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

Fault code Red LED illuminated (Overheat) 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 become too hot and has automatically shut itself down to prevent damage or safety issues. (As reported on Potterton Kingfisher MF RSL)