BoilerFaultCodes CH light On High
Boiler Fault Code CH light On
Also written as CHLIGHTON — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code CH light On appears across 1 boiler brand and 3 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has automatically turned itself off because it is getting too hot, likely due to a flow issue within your heating system. (As reported on Worcester Bosch 28 i SI)
Pick your boiler brand for the CH light On fix
Source
Information for the CH 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 7 July 2026