BoilerFaultCodes Lockout (Red) light is on High
Boiler Fault Code Lockout (Red) light is on
Also written as LOCKOUTREDLIGHTISON — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Lockout (Red) light is on 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 stopped working because it couldn't safely ignite the flame after several attempts, so it has shut down to protect itself. (As reported on Potterton Suprima HE)
Pick your boiler brand for the Lockout (Red) light is on fix
Source
Information for the Lockout (Red) light is on 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