E20
Dettson
False Flame Detection
Boiler shows E20 and indicates flame present when there should be none
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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
Shorted flame sensor to ground, Faulty Dettson ignition control, Electrical noise on flame circuit, Gas valve leaking through
How to Fix / Troubleshooting
Safety: This fault can indicate a serious combustion or gas valve issue. Turn off gas and power and contact a qualified technician. Do not attempt to run the boiler until the cause is identified.
- Inspect flame sensor wiring: With power OFF, check for damaged insulation or wires touching grounded metal.
- Check ignition control: The Dettson ignition module may be misreading flame current. A technician should test and replace if necessary.
- Gas valve leak check: A professional must verify that the gas valve fully closes when de-energized. Any leakage requires immediate valve replacement.
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Repair Difficulty
Professional Required
5/5
Required Part
Dettson ignition control module
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