Lennox 49M84 Flame Sensor

The Lennox 49M84 Flame Sensor is a critical OEM replacement part designed for precision flame rectification in gas-fired heating systems. Engineered for high-temperature resilience, this L-Bend style sensor monitors the burner's flame status, transmitting a DC microamp signal to the integrated furnace control to ensure safe and continuous operation. A failing 49M84 is often the culprit when a furnace cycles through several ignition attempts before a complete lockout. Professionals should test the existing sensor's output with a multimeter; if the HVAC flame sensor is not delivering a steady signal, it can cause the gas valve to close prematurely for safety. This genuine Lennox 49M84 is compatible with a wide range of Lennox, Allied, Armstrong, and Ducane equipment, including high-efficiency furnaces and packaged units. Replacing a carbon-fouled or cracked ceramic electrode restores the sequence of operation and prevents unnecessary service calls due to ignition failure.

• Optimized Compatibility: Direct replacement for Lennox 49M8401, 49M84, and various legacy parts across Allied and Ducane brands.
• Safety Compliance: Prevents gas buildup by ensuring the ignition control only keeps the gas valve energized when a flame is physically detected.
• Durability: Constructed from high-grade, heat-resistant materials to withstand the intense thermal environment within the burner assembly.
• System Reliability: Eliminates nuisance furnace lockout codes caused by degraded or soot-covered flame rods.

• What are the signs of a bad Lennox 49M84 sensor? The most common symptom is the burner lighting for 2–5 seconds and then immediately shutting down, eventually leading to a lockout.
• Can I clean the 49M84 instead of replacing it? While light cleaning with an emery cloth can temporarily restore flame sense, a cracked ceramic insulator or heavily pitted rod requires a full replacement to maintain reliable operation.
• Which Lennox models use this part? This sensor fits numerous Lennox units, including KGA, KGB, LGM, and LGC series rooftop and residential models.

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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.