How To Clean a Furnace Ignitor

Updated: Jul. 04, 2023

Have a gas furnace that won't light? Carbon deposits on the ignitor could be why. Learn how to clean a furnace ignitor here.

Gas furnaces offer lots of advantages. They’re easy to use, there’s no need to gather fuel and they feature fine temperature control. That’s why about half of U.S. households heat their homes with natural gas, according to the U.S. Energy Information Administration.

But gas furnaces do have some downsides. For one thing, they have a lot of complex parts. Knowing which parts need cleaning and maintenance can be difficult for homeowners. If you’ve got a gas furnace in your home, you’ll definitely need to know how to clean and maintain your furnace ignitor.

Why Do You Need To Clean a Furnace Ignitor?

Furnace ignitors require occasional cleaning to prevent carbon buildup. If your furnace suddenly won’t light, there’s a decent chance a dirty ignitor is the culprit. That’s why it’s vital to know which kind of ignitor your furnace has.

Different models have different styles of ignitors, and the cleanup procedure varies slightly from one ignitor type to the next. Look up your furnace model number to identify which ignitor you have and what it looks like, clean and dirty.

How To Identify a Furnace Ignitor

All gas furnace ignitors are housed near the burners, behind a protective metal panel you’ll need to remove to see it. If you suspect an ignitor problem but it doesn’t appear dirty, it may need to be replaced. Ignitors go bad occasionally, and having a spare on hand at all times makes sense.

How To Clean a Furnace Ignitor

If you’ve got a dirty or discolored ignitor, here’s how to clean it.

Tools and materials to clean a furnace ignitor

  • Headlamp;
  • Socket wrench set;
  • Multi-tip screwdriver;
  • Air compressor with spray nozzle attachment or cans of compressed air;
  • Medium-fine scuff pads;
  • Vacuum cleaner;

Turn off power and access the ignitor

  • Find your furnace’s main power switch and turn it off. You don’t want to furnace firing up while you’re working on it.
  • Use a wrench or screwdriver to open the access panel.
  • Switch on your headlamp and locate the hot surface ignitor near the burners.

For a hot surface ignitor or direct spark ignitor

  • Disconnect the push-on wire connector powering the ignitor.
  • Undo any bolts or screws holding the ignitor in place, then remove the ignitor. Be sure not to touch the ignitor element (for hot surface ignitors) or the spark wires (for direct spark ignitors), since skin oil can cause them to malfunction. Hold it only by the base.
  • Gently rub the metal surface of the ignitor (the element for hot surface ignitors or wires for direct spark ignitors) with a scuff pad on all sides until it’s shiny everywhere.
  • Vacuum off all dust.
  • Replace the ignitor, reconnect the wires and replace the panel.

For a standing pilot ignitor or intermittent pilot ignitor

  • Locate the pilot orifice, the place where the gas comes out that ignites the pilot flame. Examine for carbon buildup or debris.
  • Use an air compressor with a spray nozzle or a can of compressed air with a plastic straw to blow and dislodge the unwanted material.
  • Move the end of the spray nozzle or air can straw as close to the open end of the pilot orifice as possible before blowing. If there’s any buildup, it will almost certainly be inside the orifice. That’s where you need to direct the air.
  • Spray gently, not more than a second or two. Compressors have enough air pressure to potentially damage internal parts, so a light touch works best.
  • If you have an intermittent pilot system, use your compressed air to dislodge any buildup on the spark ignitor wire.