BoilerFaultCodes Blue light on Low
Boiler Fault Code Blue light on
Also written as BLUELIGHTON — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Blue light on appears across 1 boiler brand and 4 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is working perfectly, and the blue light simply indicates that it is currently powered on and ready to provide heating or hot water. (As reported on Worcester Bosch Greenstar i Junior)
Pick your boiler brand for the Blue light on fix
Source
Information for the Blue light 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