House - Furnace Parts [Lifetime Warranty] 69W43 Furnace Flame Sensor - Pack of 2
Two 69W43 furnace flame sensors with white ceramic insulators and bent metal rods.
69W43 furnace flame sensor component shown with a compatible residential gas furnace unit.
69W43 furnace flame sensor showing dimensions and 90-degree angle for Lennox, Armstrong, and Ducane furnaces.
Diagram of 69W43 furnace flame sensor highlighting the sensor head, ceramic porcelain, and mounting bracket features.
Two 69W43 furnace flame sensors with white ceramic insulation and metal mounting brackets.
Technician performing a quick installation of a 69W43 furnace flame sensor with step-by-step instructions.
69W43 furnace flame sensor replacement part shown in a lifestyle graphic with a family by a fireplace.
Two 69W43 furnace flame sensors with white ceramic insulators and bent metal rods.
69W43 furnace flame sensor component shown with a compatible residential gas furnace unit.
69W43 furnace flame sensor showing dimensions and 90-degree angle for Lennox, Armstrong, and Ducane furnaces.
Diagram of 69W43 furnace flame sensor highlighting the sensor head, ceramic porcelain, and mounting bracket features.
Two 69W43 furnace flame sensors with white ceramic insulation and metal mounting brackets.
Technician performing a quick installation of a 69W43 furnace flame sensor with step-by-step instructions.
69W43 furnace flame sensor replacement part shown in a lifestyle graphic with a family by a fireplace.
Lifetime Warranty

[Lifetime Warranty] 69W43 Furnace Flame Sensor - Pack of 2

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69W43 Furnace Flame Sensor - Pack of 2

Key Features

  • Package contains two (2) 69W43 flame sensors.
  • Detects burner flame to enable safe and continuous furnace operation.
  • Constructed with a durable cermet insulator and a corrosion-resistant sensing rod.
  • Angled probe design for direct replacement and optimal positioning.

Replaces / Cross-Reference Part Numbers

  • 69W43
  • 69W4301
  • LB-74940B
  • LB74940B
  • PSE-L79 (102431-02)

Compatibility & Fitment

  • Designed as a direct replacement part for specific furnace models from:
  • Lennox
  • Ducane
  • Armstrong
  • Note: Always confirm compatibility by checking your equipment's service manual and part number.

When to Replace

  • Furnace ignites but shuts down after a few seconds.
  • Burner flame will not stay lit.
  • Visible damage, such as a cracked porcelain insulator on the existing sensor.
  • Heavy carbon buildup or corrosion on the sensor rod that cleaning does not resolve.

Installation Tips

  • Disconnect all electrical power to the furnace unit before beginning installation.
  • Handle the new sensor by the porcelain base to avoid contaminating the metal rod with skin oils.
  • Ensure the sensor rod is properly positioned to be enveloped by the burner flame during operation.
  • Inspect the connecting wire for damage and ensure a secure connection.
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Product image 2
  • FIX FURNACE SYMPTOMS

    FIX FURNACE SYMPTOMS

    Yellow burner flames | Rusted flue lines | Poor energy-efficient | Exhaust smells | Constant thermostat adjustments
  • EXTREME HEAT RESISTANT

    EXTREME HEAT RESISTANT

    - Rod Maximum Temperature: 2190°F
  • SAVING SOLUTION

    SAVING SOLUTION

    Great feeling when your furnace is repaired and works efficiently - BlueStars brings DIY solutions to help you deal with any trouble.
  • SIMPLE INSTALLATION

    SIMPLE INSTALLATION

    It’s typically mounted by a 1/4” hex head screw. Carefully remove the screw to slide the sensor out. Replace with our new one.
LONG-LASTING SOLUTION

LONG-LASTING SOLUTION

Made of high-grade wear-resistant Metal and Ceramics, ensuring durability and resilience against temperature changes
PRECISION FLAME DETECTION

PRECISION FLAME DETECTION

Ensure home's safety by automatically shutting off the furnace whenever no flame is detected inside, preventing gas leaks
ENJOY YOUR LIFE WITH OUR PART INSIDE!

ENJOY YOUR LIFE WITH OUR PART INSIDE!

BlueStars - #1 source of high-quality replacement parts
Manufacturer
‎BlueStars
Part Number
‎69W43 2packs
Item Weight
‎1.58 ounces
Product Dimensions
‎1 x 1 x 1 inches
Style
‎Pack of 2
Batteries Included?
‎No
Batteries Required?
‎No
Warranty Description
‎Life time

FAQ

Based on the available cross-reference information, this flame sensor is used on specific Lennox, Armstrong, and Ducane furnace models. Compatibility is model-specific, so the safest check is to match your existing part number and furnace model before ordering.
This sensor matches part number 69W43 and is also cross-referenced to 69W4301, LB-74940B, and LB74940B.
The flame sensor verifies that the burner flame is present during ignition. If the control board does not detect flame through the sensor, it will shut off the gas valve as a safety measure. A weak or dirty sensor can cause the burners to light briefly and then shut back off.
Typical symptoms include the furnace starting normally, the burners igniting for a few seconds, then the flame shutting off and the system trying again. You may also see short cycling, intermittent heat, or a furnace that goes into lockout after repeated failed flame-proving attempts.
On many furnaces, flame sensor replacement is a straightforward service task that takes about 10 to 20 minutes. You typically need to turn off power to the furnace, remove the access panel, disconnect the sensor wire, remove the mounting screw, swap the sensor, and reinstall it. A nut driver or screwdriver is commonly all that is needed.
Yes. A flame sensor often fails to read properly because of oxidation or carbon buildup on the rod. Light cleaning with fine abrasive pad or very fine sandpaper can sometimes restore operation if the sensor is not cracked, badly corroded, or physically damaged. If cleaning does not solve the issue, replacement is the next step.
If replacing or cleaning the sensor does not help, check for poor wire connections, a bad ground path between the burner assembly and control board, burner contamination, ignition problems, or a failing control board. Restricted combustion airflow and burner flame instability can also prevent proper flame sensing.