5 FLASH
Miller
Flame Sensed with Gas Valve Off / False Flame Signal
Furnace attempts ignition but shuts down; Miller LED flashes 5 times in sequence.
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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 rollout into burner compartment, Faulty control board flame sensing circuit, Miswired neutral/ground
How to Fix / Troubleshooting
Safety: This fault can indicate unsafe flame conditions. Turn off gas and power immediately. Do not operate the furnace until the cause is identified.
- Inspect burner compartment: Remove the burner access door and look for signs of soot, scorching, or melted wiring near the burners or rollout switches. If present, contact a qualified technician to inspect the heat exchanger and venting.
- Check flame sensor wiring: Ensure the flame sensor lead is not pinched or touching metal surfaces. Inspect the ceramic insulator for cracks. Replace the flame sensor if damaged.
- Verify grounding and polarity: At the furnace junction box, confirm hot, neutral, and ground are correctly wired. An open ground or reversed polarity can cause false flame sensing. Correct any wiring issues according to local electrical codes.
- Test control board: If wiring and sensor are good but the board still detects flame when off, the Miller ignition control board may have a failed flame-sense circuit and should be replaced.
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Repair Difficulty
Professional Required
5/5
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