E09
Napoleon
Internal Control Board Fault / EEPROM Error
Furnace displays E09 and will not respond to thermostat commands
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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
Power surge or brownout damage, Corrupted control board memory, Loose control board harness connections, Faulty control board
How to Fix / Troubleshooting
Safety first: Turn off power at the breaker before touching the control board or wiring.
- Power reset: Turn off the furnace breaker for at least 5 minutes to allow the control to fully discharge. Restore power and see if E09 clears.
- Inspect connections: Remove the blower door and visually inspect all multi-pin harnesses on the Napoleon control board. Reseat each connector firmly. Look for corrosion or burned spots on the board.
- Check line voltage: Verify that the furnace is receiving stable 120 VAC (or 240 VAC where applicable). Frequent surges or low voltage can damage electronics.
- Surge protection: Consider installing a surge protector on the furnace circuit to prevent future board failures.
- When to replace: If E09 persists after reset and connection checks, the control board is likely defective and must be replaced with the exact Napoleon replacement board. Label all wires before removal to ensure correct installation.
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Repair Difficulty
Hard
4/5
Required Part
Integrated Furnace Control Board
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