How much does it cost to fix boiler error code Lights: On On On?

Typical repair cost for the boiler Lights: On On On fault is £120-280 including labour.

Lights: On On On High

Boiler Fault Code Lights: On On On

Also written as LIGHTSONONON — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code Lights: On On On 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 has detected an internal electrical communication error, likely caused by a loose wire or a fault with the main control board. (As reported on Baxi Solo 2)

Pick your boiler brand for the Lights: On On On fix

Baxi Lights: On On On 2 models

Source

Information for the Lights: On On 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