BoilerFaultCodesGlow-worm F28 Fault Code
The Glow-worm F28 fault code means: your boiler is failing to light the gas flame, which means your heating and hot water will not work until the system is reset or repaired.. It appears on 8 Glow-worm models in our database.
Technical description: Ignition fault
What causes the Glow-worm F28 fault?
This fault occurs when the boiler tries to start but cannot establish a stable flame to begin heating your water. The most common reasons include a lack of gas reaching the unit, a worn-out spark plug that can no longer light the fuel, or a internal component failing to detect that the flame is actually lit.
This fault is more frequent during extreme cold snaps, as external gas meters or pipes can freeze and restrict the flow of fuel to the boiler.
DIY fix possible
Check that your gas emergency control valve is in the 'on' position.If you have a pre-payment gas meter, ensure you have sufficient credit.Press the reset button (indicated by a flame with a line through it) for five seconds.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Avoid the next call-out bill
A cover plan would handle faults like F28: no call-out fees, no surprise bills.
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Glow-worm models that show the F28 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm F28 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 Betacom2 28 manual (PDF)
- Glow-worm Easicom 28 manual (PDF)
- Glow-worm Ultracom 2 35cxi manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026