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OEM Lennox Flame Sensor — 18G89
Lennox

OEM Lennox Flame Sensor — 18G89

SKU: LNX-18G89 Brand: Lennox
$19.95 $26.95

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Texas CMBL #19328542014
SAM.gov Registered
Govt POs Accepted

The genuine OEM Lennox 18G89 flame sensor is a critical safety component in your gas furnace. It uses the principle of flame rectification to confirm that the burners have actually ignited, sending a microamp signal back to the control board. If no flame is detected, the board shuts off the gas valve to prevent a dangerous buildup of unburned fuel. This factory part is engineered to the exact resistance and positioning specifications of your Lennox furnace.

Common failure symptoms: A failing or dirty 18G89 flame sensor is one of the most frequent causes of furnace short-cycling. You may notice the burners light and then shut off after just a few seconds, repeated ignition attempts, or the furnace locking out completely and running only cold air. Oxidation and carbon buildup on the sensor rod weaken the flame signal over time.

Why OEM matters: Aftermarket sensors often have slightly different rod length, alloy, or mounting geometry, which can produce a marginal flame signal that fails intermittently — especially frustrating on cold nights. The OEM Lennox 18G89 guarantees the correct signal strength and a precise fit for reliable, safe 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

Frequently Asked Questions

Does this Flame Sensor fit my Lennox OEM Lennox Flame Sensor — 18G89?
Yes. This is the factory-specified OEM flame sensor for the Lennox OEM Lennox Flame Sensor — 18G89. It is a direct drop-in replacement that fits without modification. Always verify the model number on your equipment nameplate before ordering.
How do I replace the flame sensor on my Lennox OEM Lennox Flame Sensor — 18G89?
Difficulty: Easy (10–15 min)
Step 1: Turn off power/gas. Step 2: Open furnace panel. Step 3: Locate flame sensor rod near burners. Step 4: Remove single mounting screw. Step 5: Clean rod with 400-grit sandpaper until shiny (or replace). Step 6: Reinstall and tighten. Most common furnace repair — saves $150–$300 vs technician.
My furnace lights then shuts off after a few seconds. Why?
Furnace lights then shuts off after 3–10 seconds = dirty flame sensor in 90% of cases. The sensor can’t detect flame through oxidation buildup. Fix: clean with 400-grit sandpaper (free, 15 min). If cleaning doesn’t work, replace the sensor.
Is this flame sensor compatible with Bryant or Payne too?
Many Lennox parts are cross-compatible with Bryant and Payne since all three brands are manufactured by Carrier Global Corporation. The same physical part is often used across brand labels with different model numbers. To verify: check your Bryant or Payne equipment service manual for cross-compatible part numbers, or email info@nationalhvacparts.com with your model number.
Should I use OEM or aftermarket for my Lennox flame sensor?
OEM recommended for reliability and warranty compatibility. OEM parts match exact factory specifications for proper fit, performance, and safety. While aftermarket alternatives cost less upfront, the risk of improper fit and reduced lifespan usually makes OEM the better value long-term.
How fast does National HVAC Parts ship?
Orders placed before 3:00 PM CST ship the same business day. Standard delivery is 2–5 business days anywhere in the continental United States. Express shipping available at checkout. We ship from Houston, TX to all 50 states. 30-day return policy on all parts.
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Mike Rivera
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