BoilerFaultCodesGlow-worm Reset light Fault Code
Also written as RESETLIGHT — same fault.
The Glow-worm Reset light fault code means: your boiler has switched itself off because it got too hot, likely triggered by a safety sensor to prevent damage.. It appears on 4 Glow-worm models in our database.
Technical description: If the overheat Safety Temperature Limiter operates as indicated by illuminated reset light, open the controls cover and turn temperature control to “0” (anticlockwise) and then back to original position.
What causes the Glow-worm Reset light fault?
This fault occurs when the water inside the boiler reaches an unsafe temperature, forcing the system to shut down for safety. It is usually caused by a failure to move heat away from the boiler quickly enough, often due to a broken pump or a blockage in the internal pipework. In some cases, a faulty sensor may mistakenly signal that the unit is overheating even when temperatures are normal.
This issue is more frequent during the first cold snap of autumn when pumps that have been idle all summer often seize up upon being switched back on.
DIY fix possible
Open the small control cover on the front of the boiler.Turn the temperature control knob fully anticlockwise to the '0' position.Wait a few seconds, then turn the knob back to your original desired temperature setting to restart the boiler.
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Glow-worm models that show the Reset light fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm Reset light 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 31 August 2026