BoilerFaultCodesGlow-worm F14 Fault Code
The Glow-worm F14 fault code means: your boiler has detected that the water inside the heating system has become dangerously hot and has shut itself down to prevent damage.. It appears on 10 Glow-worm models in our database.
Technical description: Central heating flow T° > 95°C
What causes the Glow-worm F14 fault?
This fault occurs when the boiler's main control board loses communication with the gas valve or detects an electrical signature that suggests the valve is unsafe to operate. The most common reason is a component failure within the gas valve itself, though damaged wiring or a fault on the printed circuit board can also prevent the signal from being sent correctly.
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 F14 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm F14 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