BoilerFaultCodesGlow-worm RED NEON Fault Code
Also written as REDNEON — same fault.
The Glow-worm RED NEON fault code means: your boiler has stopped working because the water pressure in the central heating system is too low.. It appears on 1 Glow-worm model in our database.
Technical description: Fill central heating system, pressure 0.7bar min.
What causes the Glow-worm RED NEON fault?
This fault occurs when there isn't enough water circulating in your central heating system to operate safely. The most common reasons are a slow leak from a radiator valve or pipework, or simply that the system needs topping up after you have bled air from your radiators.
This issue is frequently seen in autumn when homeowners turn their heating back on for the first time after summer, revealing pressure drops that occurred while the system was idle.
DIY fix possible
Locate the external filling loop, which is usually a silver flexible hose with two small valves.Open both tap handles slowly until you hear water flowing into the system.Watch the pressure gauge until it reaches between 1.0 and 1.5 bar, then close both taps tightly.The red light should extinguish and the boiler should restart automatically.
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Gas Safe Register →Glow-worm models that show the RED NEON fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm RED NEON 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