BoilerFaultCodesGlow-worm 07 Fault Code
The Glow-worm 07 fault code means: your boiler's temperature sensor for hot water has stopped working correctly, meaning your system cannot tell how hot the water is.. It appears on 6 Glow-worm models in our database.
Technical description: DOMESTIC THERMISTOR ON DHW PIPE: CIRCUITS OPEN OR SHORT CIRCUIT. CHECK RESISTANCE OF THE THERMISTOR.
What causes the Glow-worm 07 fault?
This fault occurs when the internal sensor responsible for monitoring your hot water temperature fails to send a clear signal to the main control board. The most common reason is that the sensor's internal electrical resistance has fluctuated out of range due to age, or the wiring connecting it has become loose or corroded. Because the boiler can no longer safely verify how hot the water is, it stops heating to prevent scalding or damage.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Gas Safe Register →Glow-worm models that show the 07 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm 07 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