BoilerFaultCodesGlow-worm Neon 1 lit Fault Code
Also written as NEON1LIT — same fault.
The Glow-worm Neon 1 lit fault code means: your boiler has detected an electrical supply issue, likely caused by a tripped switch, a blown fuse, or a temporary power failure.. It appears on 2 Glow-worm models in our database.
Technical description: Correct power supply problem.
What causes the Glow-worm Neon 1 lit fault?
This fault occurs when the boiler's control system detects an interruption or an irregularity in the electrical current reaching the unit. It is most commonly caused by a blown 3-amp fuse in the external spur switch or a failure within the boiler's internal circuit board which prevents it from processing power correctly.
DIY fix possible
Check your home's main fuse box (consumer unit) to see if any circuit breakers have tripped.Inspect the fused spur switch near the boiler and replace the 3-amp fuse if it has blown.Turn the boiler power switch off and back on to attempt a reset of the internal electronics.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Glow-worm models that show the Neon 1 lit fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm Neon 1 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