Lennox P/N 51M1401 (Catalog 51M14) – Genuine OEM Single-Prong Flame Sensor

The Lennox 51M1401 (also known by its Catalog Number 51M14) is a genuine OEM single-prong flame sensor designed for a wide range of Lennox, Allied, Armstrong, and Ducane gas furnaces and boilers. This critical safety component detects the presence of a flame in the combustion chamber, sending a signal to the control board to ensure safe ignition and continuous operation. If the signal is lost, the control board safely shuts off the gas flow, preventing the buildup of unburned gas and maintaining system safety. 

Being a Genuine OEM part from Lennox ensures optimal compatibility and reliability. Unlike universal alternatives, this sensor features a durable ceramic insulator and a corrosion-resistant stainless steel probe that delivers dependable performance in high-temperature environments. Its precision build ensures an exact fit and the correct micro-amp signal output required by Lennox safety circuits, preventing nuisance service calls that often occur with universal replacement parts. 

Key Features and Function:

• Accurate Flame Detection: Precisely monitors the burner flame signal to confirm successful ignition and continuous combustion.
• Genuine OEM Reliability: Official part from Lennox, ensuring perfect fitment and validated functionality for compatible units.
• Durable, High-Temp Construction: Features a high-temperature ceramic insulator and stainless steel rod for reliable operation.
• Safety Integration: Plays a vital role in preventing gas leaks and ensuring safe operation of the heating system. 

Product Details and Key Specifications:

• Brand: Lennox (Genuine OEM)
• Catalog Number: 51M14
• Model/Part Number: 51M1401
• Type: Flame Sensor, Single Prong
• Diameter: 0.114 IN
• Product Width: 3.45 IN
• Product Height: 2.8 IN
• Product Depth: 1.62 IN
• Gross Shipping Weight: 1.5 LB
• Flame Sensor Prong Dimensions: Length 2.35″, Height 2.81″ 

🛠️ HVAC Depot Pro Tip: Clean, Don't Just Replace

The most frequent cause of a furnace fault code related to the flame sensor (symptoms include the furnace lighting and then shutting off quickly) is carbon buildup on the sensor rod. Before replacing the 51M14, always try cleaning the existing rod with fine steel wool or an emery cloth. This simple maintenance step often restores the proper micro-amp signal, potentially fixing the issue without needing a new part. 

The 51M1401 is a direct OEM replacement for the following part numbers:

• OEM Numbers:

  51M1401, 51M14, 43K88, 43K8801.

• Cross-Refs:

  Supco FLS51M14. 

Extensive Model Compatibility List:

Note: Use 'CTRL+F' to search for your specific model: 

• Lennox 80MGF Series:

  80MGF2-45A (Rev 6-12), 80MGF2-60A, 80MGF2-75A, 80MGF2-75S, 80MGF3/4-100A/S, 80MGF3/4-120A/S, 80MGF4/5-100A/S, 80MGF4/5-120A/S, 80MGF4/5-140A/S, and corresponding X variants.

• Lennox 80UHG Series:

  80UHG2-45A/60A/75A, 80UHG3/4-100A/120A, 80UHG4/5-100A/120A, and corresponding X variants.

• Lennox G24 Series:

  G24-200A, G24E2/3-75A, G24M2-45A/S, G24M3-60A/S, G24M4-75A/S, and various MCE, M, E variants.

• Other Compatible Models:

  F8AUH series (e.g., F8AUH-045 to F8AUH-120), G27, and G29 series furnaces.