G20 Low

Boiler Fault Code G20

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code G20 appears across 4 boiler brands and 7 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is displaying a setting notification indicating that it is configured to run on natural gas, which is the standard fuel type for UK homes. (As reported on Main Eco Compact Combi)

Pick your boiler brand for the G20 fix

Biasi G20 2 models Glow-worm G20 1 model Main G20 3 models Sime G20 1 model

Source

Information for the G20 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