BoilerFaultCodes Light off Low
Boiler Fault Code Light off
Also written as LIGHTOFF — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Light off appears across 1 boiler brand and 10 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is currently sitting in standby mode because it hasn't received a signal from your thermostat or timer to start heating. (As reported on Worcester Bosch Highflow CDi)
Pick your boiler brand for the Light off fix
Source
Information for the Light 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