Boiler Fault Code 3 green flashes

Also written as 3GREENFLASHES — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026

Fault code 3 green flashes appears across 2 boiler brands and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has lit correctly but the flame has unexpectedly gone out, which often means the system isn't getting enough fuel or the sensor can't tell the fire is lit. (As reported on Potterton Titanium Heat)