20
Intergas
Flame Detection Fault / Flame Signal Lost
Boiler displays error code 20, boiler locks out, no heating or hot water
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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.
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Possible Causes
Dirty or damaged flame sensor (ionisation electrode), Poor earth connection, Incorrect gas/air mixture, Faulty main PCB flame detection circuit
How to Fix / Troubleshooting
Danger: Flame detection issues involve combustion safety. Do not attempt to clean or adjust electrodes or gas components yourself. Only a Gas Safe engineer may work on these parts.
- Reset once: Use the reset button to clear the fault. Observe whether the boiler lights and stays on. If the error returns, do not keep resetting.
- Check gas supply: Confirm other gas appliances work correctly. If not, contact your gas supplier.
- Check flue terminal: From outside, ensure the flue is not blocked or damaged.
- Engineer inspection: The engineer will clean or replace the flame sensor (ionisation electrode), verify correct earthing, check burner and gas valve settings, and test the PCB flame detection circuit.
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Repair Difficulty
Professional Required
5/5
Required Part
Flame Sensor (Ionisation Electrode)
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