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

Typical repair cost for the boiler ON FLASH FLASH fault is £120-£350 including labour.

ON FLASH FLASH High

Boiler Fault Code ON FLASH FLASH

Also written as ONFLASHFLASH — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code ON FLASH FLASH 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 has detected that water is not moving through the system properly or there isn't enough water inside the unit to safely heat up. (As reported on Baxi Solo)

Pick your boiler brand for the ON FLASH FLASH fix

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

Source

Information for the ON FLASH 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