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OEM Lennox Flame Sensor — 12L09
Lennox

OEM Lennox Flame Sensor — 12L09

SKU: LNX-12L09 Brand: Lennox
$19.95 $26.95

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Texas CMBL #19328542014
SAM.gov Registered
Govt POs Accepted

The genuine OEM Lennox 12L09 flame sensor confirms that your gas furnace's burner has ignited, allowing the control board to keep the gas valve open only while a true flame is present. Using flame rectification, the sensor rod conducts a small microamp current through the flame back to the board, providing the proof-of-flame signal that keeps your Lennox heating system running safely.

Common failure symptoms: A dirty, corroded, or failing 12L09 sensor typically causes the furnace to light and then shut off after a few seconds, short cycling, repeated ignition lockouts, and periods of no heat. If cleaning the rod only restores heat temporarily, the sensor has degraded and should be replaced.

Why OEM matters: Lennox furnace controls expect a precise flame-sense current, and an out-of-spec aftermarket sensor can trigger nuisance faults and unreliable ignition. The OEM 12L09 delivers the exact rod length, mounting bracket, and signal response your board is designed for, ensuring a direct fit and consistent, worry-free performance.

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 — 12L09?
Yes. This is the factory-specified OEM flame sensor for the Lennox OEM Lennox Flame Sensor — 12L09. 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 — 12L09?
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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