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

Typical repair cost for the boiler Lights Flash On On fault is £250-400 including labour.

Lights Flash On On High

Boiler Fault Code Lights Flash On On

Also written as LIGHTSFLASHONON — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 31 August 2026

Fault code Lights Flash On On appears across 2 boiler brands and 5 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's central control computer has developed an internal electrical fault and is no longer able to give instructions to the system. (As reported on Potterton Promax 15/2 HE Plus)

Pick your boiler brand for the Lights Flash On On fix

Baxi Lights Flash On On 2 models Potterton Lights Flash On On 3 models

Source

Information for the Lights Flash 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 31 August 2026