BoilerFaultCodesGlow-worm S.22 Fault Code
Also written as S22 — same fault.
The Glow-worm S.22 fault code means: your boiler is performing a routine self-check of the internal pump before starting the burner to ensure water is circulating correctly.. It appears on 21 Glow-worm models in our database.
Technical description: Pump pre run
What causes the Glow-worm S.22 fault?
This is a normal part of the boiler's startup process and occurs when the system sends power to the internal pump to get water moving. It happens every time you ask for heating or hot water to confirm the pump is spinning correctly before the flames ignite. It is not an error, but rather a brief verification step the internal computer performs to ensure the system is safe to operate.
DIY fix possible
No action is required as this is a normal operational status message, not a fault.Wait a few moments for the boiler to complete the pre-run cycle and ignite.If the code persists for a long time without the boiler firing, try a simple reset.
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Glow-worm models that show the S.22 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Glow-worm S.22 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 Ultracom 2 CXI manual (PDF)
- Glow-worm Betacom4 manual (PDF)
- Glow-worm Easicom3 Combi manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026