BoilerFaultCodesGlow-worm Green light Fault Code
Also written as GREENLIGHT — same fault.
The Glow-worm Green light fault code means: your boiler is working correctly and is simply indicating that the internal burner is lit and ready to provide heating or hot water.. It appears on 4 Glow-worm models in our database.
Technical description: Indicates that the pilot valve is held open, the thermoelectric valve and spark unit are de-energised, and the system is operating or ready.
What causes the Glow-worm Green light fault?
This indicator light means that your boiler has successfully sparked and established a flame to heat your water. It shows that the internal gas valve is open and the system is functioning exactly as it should be. There is no fault present, and the light is simply confirming that the burner is currently active.
DIY fix possible
This fault may be fixable without an engineer. Check your manual first.
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Glow-worm models that show the Green light fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm Green light fault code information on this page is sourced and cross-checked against the official Glow-worm service / installation manuals for each affected model.
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026