How much does it cost to fix boiler error code Flashing red A or B?

Typical repair cost for the boiler Flashing red A or B fault is £100-£250 including labour.

Flashing red A or B High

Boiler Fault Code Flashing red A or B

Also written as FLASHINGREDAORB — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code Flashing red A or B appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has got too hot and has shut itself down as a safety precaution to prevent damage. (As reported on Alpha FMK)

Pick your boiler brand for the Flashing red A or B fix

Alpha Flashing red A or B 1 model

Source

Information for the Flashing red A or B 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