69W43 Furnace Flame Sensor - For Lennox, Armstrong & Ducane Furnaces - Replaces 69W4301 LB-74940B LB74940B - 2 Pack

69W43 Furnace Flame Sensor

Key Features

• 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
• 102431-02
• 790-801A1

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.