BoilerFaultCodes No light / Not a fault code Low
Boiler Fault Code No light / Not a fault code
Also written as NOLIGHTNOTAFAULTCODE — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code No light / Not a fault code 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 been manually set to run at full power for testing purposes and just needs to be switched back to its normal operating mode. (As reported on Worcester Bosch Greenstar i Junior)
Pick your boiler brand for the No light / Not a fault code fix
Source
Information for the No light / Not a fault code 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