BoilerFaultCodesGlow-worm S.08 Fault Code
Also written as S08 — same fault.
The Glow-worm S.08 fault code means: your boiler is taking a short, planned break to prevent the system from turning on and off too frequently, which protects the internal components and saves energy.. It appears on 12 Glow-worm models in our database.
Technical description: Anti cycling period
What causes the Glow-worm S.08 fault?
This status occurs when the boiler has reached its target temperature and needs to pause briefly to prevent the burner from clicking on and off too quickly. It is usually triggered because the heat has nowhere to go, such as when your radiators are already hot or the room thermostat has almost reached its setting. By waiting a few minutes before firing up again, the boiler reduces unnecessary wear on the components and operates more efficiently.
This is more common during autumn and spring when the weather is milder and your home doesn't require the boiler to run at full power for long periods.
DIY fix possible
Wait for 10 to 15 minutes as this is a normal operating status and not a faultEnsure your room thermostat is turned up to your desired temperatureCheck that your radiator valves are open to allow the heat to dissipate
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 S.08 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm S.08 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