How much does it cost to fix boiler error code GM003?

Typical repair cost for the boiler GM003 fault is £150-300 including labour.

GM003 Emergency

Boiler Fault Code GM003

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code GM003 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 is detecting a flame inside the unit when it shouldn't be, which indicates a potential issue with the internal electronics or ignition system. (As reported on Baxi 400 Combi 2)

Pick your boiler brand for the GM003 fix

Baxi GM003 1 model

Source

Information for the GM003 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