BoilerFaultCodesGlow-worm d.17 Fault Code
Also written as D17 — same fault.
The Glow-worm d.17 fault code means: your boiler has detected that the water inside the system is not circulating or heating correctly, which usually suggests a problem with the way it senses the temperature or moves water around.. It appears on 11 Glow-worm models in our database.
Technical description: Flow or Return temperature control
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 d.17 fault code
Click a model for the full fault code list and model-specific repair notes.
- Compact Repair: £120-250
- Easicom 24 Repair: £150-250
- Easicom 28 Repair: £150-250
- Energy7 Combi Repair: £120-250
- Flexicom 24c / 28c Repair: £120-250
- MicraCom Repair: £100-250
- Sustain 12s Repair: £120-250
- Sustain 15s Repair: £120-250
- Sustain 18s Repair: £120-250
- Ultimate 3 25R Repair: £120-250
- Ultimate3 Combi Repair: £120-250
Source
Glow-worm d.17 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 31 August 2026