BoilerFaultCodes Lockout (Red) light will flash High
Boiler Fault Code Lockout (Red) light will flash
Also written as LOCKOUTREDLIGHTWILLFLASH — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Lockout (Red) light will flash 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 that it is running too hot and has automatically shut down to prevent damage, meaning you currently have no heating or hot water. (As reported on Potterton Suprima HE)
Pick your boiler brand for the Lockout (Red) light will flash fix
Source
Information for the Lockout (Red) light will flash 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