BoilerFaultCodesGlow-worm F7 Fault Code
The Glow-worm F7 fault code means: your boiler is having trouble measuring the temperature of your hot water, which means it cannot safely heat water for your taps.. It appears on 4 Glow-worm models in our database.
Technical description: Domestic Hot Water thermistor fault.
What causes the Glow-worm F7 fault?
This fault occurs when the internal sensor responsible for monitoring your hot water temperature fails or sends an unreadable signal to the control board. The most common reason is that the sensor has suffered electrical failure due to age, or the wiring connecting it to the main system has become loose or damaged.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Glow-worm models that show the F7 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm F7 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 7 July 2026