How to Clean or Change Your Furnace Flame Sensor

If your furnace is shutting off shortly after starting, the culprit could be a dirty flame sensor. This small part plays a big role — it tells your furnace whether a flame is present. If it can’t “see” the flame, your system shuts down for safety. Luckily, cleaning or changing a flame sensor is a simple maintenance task you can often do yourself.

What You’ll Need

• Screwdriver

• Fine-grit sandpaper, steel wool, or emery cloth

• Clean cloth

• Replacement flame sensor (if needed)

 Steps to Clean the Flame Sensor

1. Turn off power and gas to your furnace for safety.

2. Locate the flame sensor — usually a thin metal rod in front of the burner.

3. Remove the sensor with a screwdriver.

4. Gently clean the metal rod with steel wool to remove buildup. Don’t over-sand — just enough to remove oxidation.

5. Wipe it clean with a cloth.

6. Reinstall the sensor, restore power and gas, and restart your furnace.

 When to Replace Instead of Clean

If cleaning doesn’t fix the problem, or if the sensor looks damaged, it’s time to replace it. Fortunately, flame sensors are inexpensive and easy to swap out with the same steps as above — just use the new part instead of reinstalling the old one.

Quick Tip: Cleaning your flame sensor once a year (ideally before heating season) can prevent furnace shutdowns and keep your system running efficiently.

Blog provided by: HGL Handyman Services