BoilerFaultCodes Fast flash, Lockout reset: Off High
Boiler Fault Code Fast flash, Lockout reset: Off
Also written as FASTFLASHLOCKOUTRESETOFF — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Fast flash, Lockout reset: 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 experienced a sudden technical error and has locked itself to prevent damage, requiring a manual reset to attempt to clear the fault. (As reported on Worcester Bosch Greenstar 25Si)
Pick your boiler brand for the Fast flash, Lockout reset: Off fix
Source
Information for the Fast flash, Lockout reset: Off 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