BoilerFaultCodesGlow-worm F14 Fault Code
The Glow-worm F14 fault code means: your boiler has detected a problem with how it receives its gas supply, which prevents it from lighting safely.. It appears on 3 Glow-worm models in our database.
Technical description: Gas valve fault
What causes the Glow-worm F14 fault?
This fault occurs when the boiler's control board sends a signal to open the gas supply, but the valve fails to respond or the system cannot confirm that a flame has been established. The most common reason is a mechanical failure within the gas valve itself or a faulty connection in the ignition wiring that prevents the fuel from lighting. In some cases, the main circuit board may be failing to send the correct electrical instructions to the valve.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →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 27 April 2026