Boiler displays E20, burner shuts down unexpectedly during operation without obvious cause.
Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
Possible Causes
How to Fix / Troubleshooting
Safety first: Gas-related faults must be handled by a qualified gas engineer. Do not attempt to adjust gas settings yourself.
User-level checks:
- Note if other gas appliances are affected (e.g. hobs going out), which may indicate a supply issue.
- Reset the boiler and observe if the error recurs frequently.
Technical checks (qualified personnel):
- Check inlet gas pressure and stability under load.
- Inspect and clean the burner and flame sensor; ensure correct positioning.
- Verify flame signal strength at the PCB during operation.
- Test the gas valve for stable operation and replace if intermittent.
- Perform combustion analysis and adjust as required.
If flame loss continues despite correct gas supply and combustion, further PCB diagnostics or replacement may be necessary.
Repair Difficulty
Required Part
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