Lennox 40L81 Flame Sensor Kit

The Lennox 40L81 Flame Sensor Kit is the critical genuine OEM replacement for maintaining combustion safety in Lennox HVAC systems. Engineered as a direct 1:1 substitute for 40L8101 and LB-94701A, this kit is vital for the SureLight ignition system found in G23, G26, G32, and 90UGF series furnaces. As a veteran-grade HVAC flame rod, it utilizes flame rectification to signal the control board, ensuring the gas valve remains bridged only when a stable burner flame is present. Replacing a fouled or cracked Lennox furnace flame sensor prevents common nuisance short cycling and ignition lockout codes. This professional-grade HVAC part includes an L-style sensor, a specialized mounting bracket for early-production compatibility, and a #7 mounting screw, providing a comprehensive solution for field service and preventative maintenance.

Key Benefits:

• Direct OEM Compatibility: Specifically designed to replace 40L8101 and LB-94701A without field modifications on standard units.
• Enhanced Combustion Safety: High-precision flame detection prevents unburned gas accumulation by instantly closing the valve if the flame is lost.
• SureLight System Integration: Fully compatible with Lennox SureLight ignition controls for accurate microamp signal strength.
• Complete Installation Kit: Includes the 90-degree flame sensor rod, bracket, and hardware required to retrofit early production G26 and G32 models.
• Durable Construction: Built with high-temperature ceramic insulation and professional-grade alloys to resist carbon buildup and oxidation.

Common Questions:

How do I know if my Lennox flame sensor is bad?
If your furnace ignites but shuts down after 2 to 5 seconds, it often indicates the sensor is not sending a microamp signal back to the board. Check for soot buildup or cracks in the ceramic insulator.

Can I clean the 40L81 rather than replacing it?
While cleaning with an emery cloth can provide a temporary fix for carbon buildup, a pitted or oxidized sensor will lose sensitivity. Replacing with a genuine 40L81 kit ensures long-term reliability and system safety.

Does this kit include the mounting bracket?
Yes, the 40L81 kit includes a specialized bracket because early production G26, G32, and 90UGF units require both the sensor and bracket to be replaced for proper alignment in the flame path.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.