BoilerFaultCodes Lockout (Red) flashing High
Boiler Fault Code Lockout (Red) flashing
Also written as LOCKOUTREDFLASHING — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Lockout (Red) flashing 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 sensed it is getting too hot and has shut itself down as a safety precaution. (As reported on Potterton Performa SL HE 9 2)
Pick your boiler brand for the Lockout (Red) flashing fix
Source
Information for the Lockout (Red) 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