BoilerFaultCodesGlow-worm Burner On neon off Fault Code
Also written as BURNERONNEONOFF — same fault.
The Glow-worm Burner On neon off fault code means: your boiler's burner stays lit even when it should turn off, meaning it isn't responding to your thermostat or timer settings.. It appears on 4 Glow-worm models in our database.
Technical description: The burner will remain alight until switched off by the control thermostat, any remote control or the programmer.
What causes the Glow-worm Burner On neon off fault?
This fault occurs when the boiler loses its ability to regulate the flame, causing the burner to stay lit regardless of your heating settings. The most common reason is a malfunctioning main circuit board or a faulty gas valve that has become stuck in the open position. It can also be caused by a wiring error in your external thermostat or programmer that is continuously sending a 'heat on' signal.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Glow-worm models that show the Burner On neon off fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm Burner On neon off fault code information on this page is sourced and cross-checked against the official Glow-worm service / installation manuals for each affected model.
- Glow-worm Micron 60FF manual (PDF)
- Glow-worm Micron 40FF manual (PDF)
- Glow-worm Micron 50FF manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026