Can a flame sensor be intermittent?

The flame sensor is a safety component that detects whether or not there is a flame in the combustion chamber. If this sensor is dirty, the dirt can cause the sensor to operate intermittently. When this happens, your furnace will most likely light, but because the sensor can’t properly detect if a flame is present.

How do you troubleshoot a flame sensor?

Quote from the video:
Quote from Youtube video: Board if this is loose or broken. Off sometimes that will cause your flame sensor issue as well so you clean up your flame sensor you plug it in but it's still doing the same problem.

How do you test a flame sensor on a furnace?

Quote from the video:
Quote from Youtube video: And connect one of the probes. Coming off the meter to the wire that you just disconnected. You're going to stick the probe between the insulation. And the back of the clip.

How do you clean a flame sensor rod?

Quote from the video:
Quote from Youtube video: Now there's the flame sensor. And all we have to do to clean this is just to take a little piece of Emery paper. And sand it slightly. So if you don't have any of the sand. Cloth.

What symptoms would a furnace with a dirty flame sensor exhibit?

Signs of a bad furnace flame sensor are:

  • The furnace lights but then shuts down after a few seconds (short cycles)
  • The porcelain on the flame sensor is cracked.
  • The flame sensor is sooty or corroded.


Why does my furnace keep losing flame?

Your furnace has a limit switch that keeps it from running if the heat exchanger is too hot. Dirty filters, closed or blocked vents and other blockages in airflow are common causes of an overheated furnace. A bad limit switch. The limit switch may be bad and need to be replaced.

How much does a flame sensor cost for a furnace?

Flame Sensor



If the sensor is bad, it won’t be able to sense heat and will turn the furnace off. The average cost to repair or replace a flame sensor is between $75–$200.

What causes a gas furnace to kick on and off?

So, if your furnace keeps turning off and on too quickly, your thermostat might be malfunctioning or broken. There are several things that could be causing your thermostat to not work properly. The wiring could be old and need replacing, it might need new batteries, or it could be the location of your thermostat.

Do flame sensors wear out?

Do flame sensors wear out? Flame sensors wear over time. However, often the problem is a dirty sensor, rather than a broken one. Since these sensors are designed to have a low tolerance for reading variations, they might misread from the slightest carbon coating.

How long do furnace flame sensors last?

If you’ve just replaced the sensor or had a new furnace installed, you can expect the flame sensor to last for about five years. The average lifespan of a furnace is 15 to 30 years, so you can anticipate a flame sensor replacement once or twice over the course of your homeownership.

How often should you clean the flame sensor in a furnace?

Even if the flame sensor is in proper working order, it is advised that you replace it every two or three years as a preventative measure.

Why do I have to keep cleaning my flame sensor?

It is a sensitive sensor so any type of dust or carbon buildup could cause it to malfunction. Most people have their furnaces in a basement or laundry area where there is excess dust in the air. This dust could stick to the sensor making it dirty and causing your furnace to shut down.

Do all gas furnaces have a flame sensor?

Not every furnace has a flame sensor. If your furnace has a spark ignitor and not a flame sensor rod, then that ignitor is acting as a sensor. HOW IT WORKS: The control board sends electricity to the flame sensor.

Why do flame sensors fail?

Possible Causes of a Flame Sensor Malfunction



The most common is that it is dirty. Because burning fuel of any kind produces trace amounts of moisture, over prolonged exposure to these conditions, metal will rust. Since your sensor is made of metal, rust can build up, preventing proper sensing of the flame.

What can I use to clean my furnace flame sensor?

Quote from the video:
Quote from Youtube video: We got our furnace opened you know I've already got the flame sensor loosened up so I'm going to do is I'm gonna reach in and slide that depending on the furnace you have you may have flame sensor in

Where is furnace sensor located?

A furnace flame sensor is a very basic part of your furnace. It’s located on the burner assembly and is just a thin metallic rod. It’s usually bent, and it sits just in front of the pilot flame inside the furnace.

Where is the flame sensor located?

Quote from the video:
Quote from Youtube video: So the right side of the furnace.