Boiler Fault Code Fast flash (Reset button Off)

Also written as FASTFLASHRESETBUTTONOFF — same fault.

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

Fault code Fast flash (Reset button Off) appears across 1 boiler brand and 1 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 a critical internal error and has safely shut itself down to prevent damage, meaning you currently have no heating or hot water. (As reported on Worcester Bosch Greenstar i Junior)