OEM Lennox Flame Sensor — 19D31
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30-Day Returns
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The genuine OEM Lennox 19D31 flame sensor is a critical safety component in your gas furnace. It uses flame rectification to confirm that the burner has actually lit, signaling the control board to keep the gas valve open only when a real flame is present. This protects your Lennox equipment and home by preventing raw gas from flowing when ignition fails.
Common failure symptoms: When the 19D31 sensor becomes dirty, corroded, or worn, your furnace will typically light briefly and then shut down after a few seconds — a condition known as short cycling. You may also experience repeated ignition lockouts, no heat on demand, or the blower running without producing warm air.
Why OEM matters: Lennox furnace control boards are calibrated to expect a precise microamp signal from the flame sensor. Aftermarket sensors often fall outside this range, causing nuisance faults, unreliable ignition, and premature lockouts. The OEM 19D31 guarantees the correct rod length, mounting geometry, and signal characteristics for a direct fit and dependable operation season after season.
Shipping Information
- Orders placed before 3PM CST ship same business day
- Standard delivery: 2-5 business days
- Express shipping available at checkout
- Free shipping on orders over $75
- Tracking number emailed upon shipment
Return Policy
- 30-day returns on unused parts in original packaging
- Electrical parts (capacitors, contactors, control boards) are final sale once installed
- Email info@nationalhvacparts.com to initiate a return
- Refunds processed within 5-7 business days