BoilerFaultCodesGlow-worm Connection Fault Code
Also written as CONNECTION — same fault.
The Glow-worm Connection fault code means: your boiler's main internal computer and the front control panel have lost contact, meaning the system cannot receive instructions to provide heating or hot water.. It appears on 11 Glow-worm models in our database.
Technical description: No communication between the PCB and the user interface. Electronics defective
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 Connection fault code
Click a model for the full fault code list and model-specific repair notes.
- 30cxi Repair: £180-350
- 38cxi Repair: £180-350
- Energy Repair: £150-300
- Energy Regular Repair: £180-350
- Energy System Repair: £150-300
- Energy7 Combi Repair: £150-300
- Energy7 Regular Repair: £150-350
- Energy7 System Repair: £150-300
- Sustain 12s Repair: £140-350
- Ultimate 3 25R Repair: £200-350
- Ultracom hxi Repair: £180-350
Source
Glow-worm Connection 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 7 July 2026