BoilerFaultCodesGlow-worm NEON3 Fault Code
The Glow-worm NEON3 fault code means: your boiler has stopped working because it thinks the fan is spinning but it isn't receiving the correct signal to proceed with lighting the burner.. It appears on 12 Glow-worm models in our database.
Technical description: FAN RUNNING
What causes the Glow-worm NEON3 fault?
This fault occurs when the boiler's internal computer detects that the fan is spinning, but the safety sensor fails to confirm that air is actually moving through the system. The most common reason is a sticking air pressure switch or a fan that has become sluggish due to a build-up of dirt and debris over time. Because the boiler cannot guarantee that harmful exhaust fumes are being safely pushed outside, it shuts down as a safety precaution.
This issue often surfaces during the first cold spell of autumn when a boiler that has been idle over summer is suddenly asked to work at full capacity, causing weakened components like the fan or pressure switch to fail.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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 NEON3 fault code
Click a model for the full fault code list and model-specific repair notes.
- Fuelsaver Complheat 40 55 Repair: £150-350
- Hideaway 100 Repair: £120-280
- Hideaway 40B Repair: £120-280
- Hideaway 80 Repair: £120-280
- Micron 30ff Repair: £140-£320
- Micron 40FF Repair: £140-£320
- Micron 50FF Repair: £140-£320
- Micron 60FF Repair: £140-£320
- Space Saver Repair: £180-350
- Space Saver 30 40 50 Repair: £180-350
- Ultimate Repair: £140-£320
- Ultimate3 Repair: £140-£320
Source
Glow-worm NEON3 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