How much does it cost to fix boiler error code BURNER Slow flash?

Typical repair cost for the boiler BURNER Slow flash fault is £250-450 including labour.

BURNER Slow flash High

Boiler Fault Code BURNER Slow flash

Also written as BURNERSLOWFLASH — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code BURNER Slow flash appears across 1 boiler brand and 3 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's electronic control brain is experiencing a malfunction and can no longer safely manage the burner operation. (As reported on Grant Vortex Eco External Wall Hung)

Pick your boiler brand for the BURNER Slow flash fix

Grant BURNER Slow flash 3 models

Source

Information for the BURNER Slow 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 7 July 2026