How much does it cost to fix boiler error code On * On Off?

Typical repair cost for the boiler On * On Off fault is £150-250 including labour.

On * On Off High

Boiler Fault Code On * On Off

Also written as ONONOFF — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code On * On Off 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 stopped working because a sensor that measures the water temperature is providing incorrect information, causing the system to shut down for safety. (As reported on Potterton Promax FSB 30HE)

Pick your boiler brand for the On * On Off fix

Potterton On * On Off 1 model

Source

Information for the On * On 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