E109
Navien
Internal Fan / Blower Speed Feedback Fault
Navien furnace shows E109, unit may not start or may shut down unexpectedly
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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
Failed combustion fan motor, Blocked fan wheel, Faulty fan speed sensor, Loose fan connector
How to Fix / Troubleshooting
Safety: Turn off power and gas before servicing the combustion fan.
- Access the fan assembly: Remove the front cover and locate the combustion fan at the top of the heat exchanger.
- Inspect fan wheel: Check for debris, dust buildup, or foreign objects in the fan wheel. Clean with a soft brush and vacuum. Ensure the wheel spins freely by hand.
- Check wiring: Verify that the fan motor connector is fully seated on the PCB and that the harness is not damaged.
- Test fan operation: Restore power briefly and call for heat while observing the fan. If it does not start or runs erratically, turn power back off. The fan motor or its internal speed sensor may be defective.
- Replace fan if needed: Remove mounting screws and gasket, disconnect wiring, and install a new Navien OEM combustion fan assembly. Ensure proper sealing to prevent flue gas leaks.
- Reset and test: Restore power and gas, reset the unit, and verify stable fan operation and absence of E109.
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Repair Difficulty
Hard
4/5
Required Part
Combustion Fan Motor
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