Boiler Fault Code Flame On Before Gas On

Also written as FLAMEONBEFOREGASON — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026

Fault code Flame On Before Gas On appears across 1 boiler brand and 5 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's safety sensor detects a flame before the gas valve has even been told to open, which usually means a internal component is stuck or sending a false signal. (As reported on Ideal Logic Code Combi ESP1)