Neon 2 NOT lit High

Glow-worm Neon 2 NOT lit Fault Code

Also written as NEON2NOTLIT — same fault.

The Glow-worm Neon 2 NOT lit fault code means: your boiler has switched itself off to prevent overheating because the system is getting too hot or the water is not circulating properly.. It appears on 7 Glow-worm models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Control thermostat overheat or pump failure cut-off devices operated. Faulty pump.

What causes the Glow-worm Neon 2 NOT lit fault?

This fault occurs when the water inside the boiler reaches an unsafe temperature, triggering a safety switch to shut the system down. The most common reasons are a pump that has stopped circulating water or a blockage in the pipework that prevents heat from escaping the boiler. Just like an engine overheating, the boiler stops to prevent internal damage to its components.

This issue often appears when the heating is turned back on for the first time in autumn, as pumps can seize up after being idle throughout the summer months.

Typical repair cost £180-450 (including labour)

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 Neon 2 NOT lit fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Glow-worm Neon 2 NOT lit 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 27 April 2026