Off High

Boiler Fault Code Off

Also written as OFF — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code Off appears across 2 boiler brands and 8 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's burner has detected light when it should be dark inside, causing it to shut down for safety. (As reported on Grant Vortex Blue)

Pick your boiler brand for the Off fix

Biasi Off 2 models Grant Off 6 models

Source

Information for the 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