Gas Furnace Flame Sensor Troubleshooting and Repair Video

Is your gas furnace short cycling on and off? In many cases, if the furnace startup sequence gets as far as ignition then immediately shuts back off, it can generally be traced to the Flame Sensor.

Your gas furnace flame sensor is just one part a built in safety system for your furnace.

Flame Sensor Troubleshooting and Quick Fix Video



6 Responses to “Gas Furnace Flame Sensor Troubleshooting and Repair Video”
  1. The flame sensor uses the flame from the main burner to prove flame at the circuit board by measuring conductivity to ground through the flame. This is the way to fix the flame sensor. But the guy in video calls it a thermocouple. You do not sand a thermocouple ,” you replace it. ”

    The thermocouple sensor is found at the business end of the pilot flame and is designed to be placed in the hottest part of the flame. The other end is connected to the pilot gas valve body. As the thermocouple heats up, it produces a small amount of electricity and when it gets hot enough from the pilot, send a signal to open the gas valve by using a solenoid operated by a 24 volt transformer.
    This has been replace by the flame sensor rod for the past 15 years however, most gas water heaters use thermocouple today. Replace a thermocouple sanding it will not help.
    B&E Air conditioning service dept.

  2. Mark says:

    Thanks for the tip and clarification Eddie!

    I didn’t even hear him talk about the thermocouple until you mentioned it!

  3. Jamie says:

    Thanks for the tip, it worked perfectly!

  4. Ted says:

    Thank you very much for the advice. Worked and saved me a service call on a Saturday night when the temp is 10 degrees on a cold Ohio night. Very easy fix. Thanks again.

  5. Mark says:


    Glad to hear we could help. Hope your flame sensor doesn’t need anymore trouble shooting!

  6. Jana says:

    Thanks so much for posting the video! It took longer to find my tools than to make the repair 🙂

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