BoilerFaultCodes Fast Flashing High
Boiler Fault Code Fast Flashing
Also written as FASTFLASHING — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Fast Flashing 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 computer error that prevents it from starting, meaning you currently have no heating or hot water. (As reported on Worcester Bosch 28i Junior)
Pick your boiler brand for the Fast Flashing fix
Source
Information for the Fast Flashing 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