Lights On On Flash High

Boiler Fault Code Lights On On Flash

Also written as LIGHTSONONFLASH — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code Lights On On Flash 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 internal computer has developed a fault and is failing to communicate with the rest of the unit, meaning it will not operate until repaired. (As reported on Potterton Promax 15/2 HE Plus)

Pick your boiler brand for the Lights On On Flash fix

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

Source

Information for the Lights On On Flash 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