Where Is The Ignition Sensor On My Furnace?

Troubleshooting an Electronic Ignition Furnace That Won't Light
Troubleshooting an Electronic Ignition Furnace That Won't Light from www.thespruce.com

Where is the Ignition Sensor on My Furnace? – 2023 Article


If you’re experiencing issues with your furnace not igniting or not staying lit, it’s possible that the ignition sensor is to blame. The ignition sensor plays a crucial role in the furnace’s ignition process, ensuring that the burners ignite and stay lit to produce heat. In this article, we will discuss the importance of the ignition sensor and help you locate it on your furnace.

What is an Ignition Sensor?

An ignition sensor is a component in a furnace that detects whether the burners have ignited successfully. It is typically a small device located near the burners. Once the burners are ignited, the sensor sends a signal to the furnace control board to continue supplying gas to the burners. If the sensor fails to detect a flame, it will signal the control board to shut off the gas supply, preventing the accumulation of unburned gas.

Locating the Ignition Sensor

The exact location of the ignition sensor can vary depending on the make and model of your furnace. However, in most cases, it can be found near the burners, either in the burner assembly or on the flame rod. The flame rod is a metal rod positioned in the path of the burner flame. It acts as a sensor, detecting whether the flame is present or not. The flame rod is usually connected to the furnace control board with a wire.

Identifying the Ignition Sensor

The ignition sensor is typically a small, metallic rod with a ceramic base. It may have a white or beige color and is often surrounded by wires or connected to the flame rod. Some ignition sensors may also have a protective cover or casing. Refer to your furnace’s manual or consult a professional if you’re having trouble identifying the ignition sensor.

Steps to Check and Clean the Ignition Sensor

If you suspect a faulty ignition sensor, here are the steps to check and clean it:

  1. Turn off the furnace and disconnect the power supply.
  2. Locate the ignition sensor near the burners or flame rod.
  3. Remove any protective cover or casing, if present.
  4. Gently clean the ignition sensor using a soft cloth or fine-grit sandpaper.
  5. Inspect the sensor for any signs of damage or corrosion.
  6. If the sensor appears damaged, consult a professional for a replacement.
  7. Reinstall the ignition sensor, ensuring it is securely in place.
  8. Restore power to the furnace and test it to see if the issue is resolved.

When to Seek Professional Help

If you’re uncomfortable performing the above steps or if the issue persists even after cleaning the ignition sensor, it’s best to seek professional help. A qualified HVAC technician can diagnose and repair any underlying issues with your furnace, ensuring its safe and efficient operation.


The ignition sensor is a vital component in your furnace’s ignition process. Knowing its location and how to check and clean it can help you troubleshoot ignition-related issues. However, always prioritize your safety and consult a professional if you’re unsure or unable to perform the necessary steps. A well-maintained ignition sensor will ensure your furnace operates reliably, keeping you warm and comfortable during the colder months.