E9
Dettson
Gas Valve Circuit Fault
Dettson furnace displays E9; blower may run but burners do not light.
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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
Open or shorted gas valve coil, Loose gas valve wiring connector, Faulty control board gas valve relay, Incorrect gas valve replacement
How to Fix / Troubleshooting
Safety first: Turn off power and shut off gas at the manual valve before touching the gas valve or piping.
- 1. Inspect gas valve wiring: Locate the gas valve on the gas manifold. Check the 2- or 3-wire connector for tight fit and signs of heat damage. Reseat the connector.
- 2. Check for miswiring after prior service: If the gas valve was recently replaced, verify that the correct Dettson-specified valve is installed and wired according to the wiring diagram on the furnace.
- 3. Test coil resistance (advanced DIY): With power off and wires disconnected, measure resistance across the gas valve coil terminals with a multimeter. An open circuit or extremely low resistance indicates a bad coil.
- 4. Observe ignition sequence: Restore power and gas, call for heat, and watch for the ignitor to glow. If the ignitor glows but there is no click from the gas valve and no flame, the valve may not be opening.
- 5. Replace gas valve (technician recommended): Gas valve replacement requires leak testing and proper adjustment. This should be performed by a licensed gas technician using the correct Dettson replacement part.
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Repair Difficulty
Professional Required
5/5
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