BoilerFaultCodes DEMAND LIGHT ONLY Low
Boiler Fault Code DEMAND LIGHT ONLY
Also written as DEMANDLIGHTONLY — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code DEMAND LIGHT ONLY appears across 1 boiler brand and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is correctly telling you that it has already reached the temperature you asked for and is simply waiting for the water to cool down before heating it up again. (As reported on Worcester Bosch 24i/28i Junior)
Pick your boiler brand for the DEMAND LIGHT ONLY fix
Source
Information for the DEMAND LIGHT ONLY 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