Lennox P/N 17J56 (T6-2108) – Genuine OEM Replacement Flame Sensor

The Lennox 17J56 (also known as Catalog Number 17J56 and Manufacturer Part Number T6-2108) is a genuine OEM flame sensor designed specifically for use in a wide range of Lennox, Allied, Armstrong, Concord, and Ducane gas-fired furnaces and unit heaters. This critical safety component detects the presence of a flame within the combustion chamber, providing a continuous signal to the control board. If the control board does not receive this signal, it safely shuts off the gas flow, preventing the buildup of unburned gas and maintaining the safety of the heating system. 

Being a Genuine OEM part from Lennox ensures optimal compatibility and reliability. Unlike universal or generic alternatives, this sensor is built with high-temperature resistant materials (glazed L-5 steatite insulator and copper-plated plate) to the exact specifications required by the furnace's safety circuits. This precision fit and validated functionality are crucial for preventing nuisance shutdowns and ensuring dependable, long-term performance. 

Key Features and Function:

• Accurate Flame Detection: Monitors the burner flame to confirm safe ignition and continuous burner operation.
• Genuine OEM Reliability: Official part from Lennox, ensuring perfect fitment and validated functionality for compatible units.
• Durable Construction: Built with high-temperature resistant materials designed to withstand temperatures up to 2200°F within the combustion chamber.
• Safety Integration: Plays a vital role in preventing gas leaks and ensuring safe operation of the heating system. 

Product Details and Key Specifications:

• Part Number: 17J56
• Manufacturer: Lennox (Genuine OEM)
• Part Type: Flame Sensor
• Catalog Number: 17J56
• Model/Part #: T6-2108
• Dimensions: 7.5 in (Height) x 3.05 in (Width)
• Diameter: 0.114 in (Probe Diameter)
• Gross Shipping Weight: 2.5 LB
• Materials: Glazed L-5 steatite insulator; copper-plated plate; nickel-plated steel male terminal. 

🛠️ HVAC Depot Pro Tip: The Annual Cleaning

The most common cause of a faulty flame sensor (leading to a furnace that runs for a few minutes and then shuts off) is a buildup of carbon and oxidation on the sensor rod. Before replacing the T6-2108, try cleaning the existing rod with a light scrub using fine steel wool or an emery cloth. This often restores the sensor's ability to detect the micro-amp current of the flame, potentially saving a service call or the cost of a new part. 

The 17J56 is a direct OEM replacement for the following part numbers:

• OEM Numbers:

  17J56, T6-2108, 65209300, 17J5601, 20516002.

• Allied/Armstrong/Ducane:

  66953. 

Extensive Model Compatibility List:

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

• Lennox LD24 Series:

  LD24-75(A, S), LD24-100(A, S), LD24-125(A, S), LD24-150(A, S), LD24-200(A, S), LD24-250(A, S), LD24-300(A, S) (Various Revisions 01-04).

• Lennox LF24 Series:

  LF24-30A, LF24-45A, LF24-50(A, S), LF24-60A, LF24-75(A, S), LF24-100(A, S), LF24-115(A, S), LF24-125(A, S), LF24-145(A, S), LF24-150(A, S), LF24-175(A, S), LF24-200(A, S), LF24-230(A, S), LF24-250(A, S), LF24-300(A, S), LF24-345(A, S), LF24-400(A, S) (Various Revisions).

• Other Compatible Models:

  Specific models in the CGHA30, CGHA45, and CGHA60 series