How much does it cost to fix boiler error code FLASH ON ON?

Typical repair cost for the boiler FLASH ON ON fault is £280-450 including labour.

FLASH ON ON High

Boiler Fault Code FLASH ON ON

Also written as FLASHONON — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code FLASH ON ON appears across 2 boiler brands and 28 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 an electrical fault and is unable to control the heating process. (As reported on Baxi Solo)

Pick your boiler brand for the FLASH ON ON fix

Baxi FLASH ON ON 24 models Potterton FLASH ON ON 4 models

Source

Information for the 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 27 April 2026