Boiler Fault Code Green/Red flashing

Also written as GREENREDFLASHING — same fault.

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

Fault code Green/Red flashing appears across 1 boiler brand and 5 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 light inside the combustion chamber when it should be dark, causing it to lock itself out as a safety precaution. (As reported on Grant Vortex Eco)