5 FLASHES
York
Flame Sensed With Gas Valve Off / False Flame Signal
York furnace attempts ignition but shuts down quickly; LED shows 5 flashes.
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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, Flame sensor wire shorted to burner, Faulty control board flame circuit, Induced draft motor backfeeding flame signal
How to Fix / Troubleshooting
Safety: Turn off power and gas before touching burner components.
- Inspect flame sensor: Remove the flame sensor rod. Check that the ceramic insulator is intact and not cracked. Ensure the metal rod is not touching the burner or grounded metal when installed.
- Check wiring: Follow the flame sensor wire back to the control board. Look for bare spots, pinched sections, or contact with sharp metal edges. Repair or replace damaged wiring.
- Clean sensor: Even though this code is for false flame, a dirty sensor can confuse the board. Lightly clean with fine steel wool and reinstall.
- Reset furnace: Restore power and call for heat. If the 5-flash code returns immediately before ignition, the control board flame-sensing circuit may be defective.
- Professional service: A technician can measure microamp flame current and verify if the board is misreading. Board replacement should be done with the correct York OEM control.
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Repair Difficulty
Hard
4/5
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