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Why Does My Gas Fireplace Keep Going Out?

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Settling down in front of a warm glowing fire on a chilly evening is the definition of cozy. There is nothing like it. Unfortunately, there is nothing like having the fire suddenly go out, leaving you

to shiver. 

Your gas fireplace keeps going out usually because a sensor or valve needs to be cleaned or replaced. The oxy pilot, which monitors fireplace oxygen levels, thermopile or thermocouple, which regulates the gas flow, is usually at fault. In rare cases, you may have a gas leak.

In this article, I’ll detail how you can repair your gas fireplace yourself and when to call in the experts. I’ll even throw in a YouTube video to walk you through the repair process.

Let’s start by getting familiar with the inner workings of your gas fireplace.

It All Begins With the Pilot Light

Most gas fireplaces have a pilot light that burns a very low flame even when the fireplace is not in use. It serves as an ignition source for the release of gas when the fireplace is lit. I’ll tell you more about the pilot light later.


The thermocouple monitors the temperature of your fireplace. It keeps the tube sending gas to the pilot open. To function, it must always be in contact with the pilot light flame. 


Thermopile functions similarly to the thermocouple but regulates the flow of gas to the fireplace. A thermopile generates more electricity than a thermocouple, so it can be used with a thermostat to regulate the heat.


The Oxypilot is a safety device that protects you and your loved ones from getting carbon monoxide poisoning. If there is not enough oxygen, the Oxypilot stops the flow of gas to your fireplace.

If the oxy pilot becomes clogged, it senses a drop in oxygen. That results in the flame changing shape, pulling away from the thermocouple and triggering a shutdown of your fireplace by cutting off the gas flow.

What if You Smell Gas

Suppose you smell gas, you should open the windows and doors to ventilate the house. If the smell is strong, leave your home immediately and call your natural gas provider; if you can not reach your gas company, dial 911 and report the emergency.  

Err on the side of safety.

Start With the Pilot Light

One of the simplest fixes to a temperamental gas fireplace is to check the pilot light. If it is not lit you may have spotted your problem.

Located on a wall inside the fireplace or behind the logs, the pilot light may be operated with a key or a control panel.  

If you can’t find your key, you can purchase a replacement at most home improvement stores. You will have to check your owner’s manual to know what kind of key works in your fireplace.

Remove the front cover of your fireplace to access the control panel or, in the key models, the gas valve knob.

If Your Fireplace Has a Key

  • Insert key into the gas valve knob.  
  • Hold a long lighter up to the burner and ignite it.
  • With the key, turn the gas valve knob half a turn counterclockwise. Gas will be released, causing the pilot to light.

If Your Fireplace Has a Control Panel

  • Switch the control knob to “off.” Wait five minutes for gas to clear.
  • Turn the shutoff valve until it is parallel with the gas line.
  • When you’re ready to light the pilot light, move the control knob to the “pilot” position.
  • Press and hold the control knob down while pressing the ignition switch. Usually, the ignition switch is red. You may have to press it several times.
  • Hold the control knob at least 30 seconds or longer to give the thermocouple time to heat and register that the pilot is active.
  • Turn the control knob to “on.” This should keep the pilot lit.

Once your pilot is on, check its color. A healthy pilot light should be dark blue around the edges with a lighter blue center. If the flame is yellow or red, the gas is contaminated.  

Contaminated gas can come from burning rust, excess air in the system, oil, soot, or dirt. All these things can give off toxic chemicals. A yellow flame could also indicate a carbon monoxide leak. If you see a yellow flame, switch off the unit and make repairs.

Clean the Pilot Light

To clean the pilot light:

  1. Turn off the gas supply to the fireplace.
  2. Remove the pilot light and clean off any buildup with a wire brush.
  3. For hard-to-reach places, use compressed air.

After cleaning the pilot light, try lighting it again. If the pilot does not stay lit, you probably have a problem with the thermocouple. If the pilot is lit but the fireplace isn’t, the problem may be the thermopile.

Checking Voltage on Thermopile and Thermocouple

If you have a multimeter, you can check the voltage on both the thermopile and thermocouple.  

Using the manufacturer’s guide, you can locate the electric contacts labeled TH/PT and PT and place the multimeter leads on each. If the thermopile voltage is below 300 millivolts, it should be replaced. A reading under 25 millivolts on the thermocouple means it should be replaced.

Clean before replacing

You will find the thermopile or thermocouple near the pilot light. With a stainless steel brush or fine grain sandpaper, delicately clean away any dirt or soot.

Relight the fireplace. You may have fixed your problem. If the fire goes out, turn off the gas and check the oxy pilot.

Unscrew the oxy pilot (you may need pliers). Using a straw or compressed air, blow through each hole in the oxy pilot. Once all holes are clear, reinstall the device.

Light the fire again. If you’re still having trouble, clean out the pilot light’s gas entry using compressed air or a cloth.

If all of the above fails, it’s time to replace your sensors and oxy pilot.

Time To Call a Professional

If you have some experience working on gas fireplaces and a good manual that will walk you through part replacement in a clear manner, you could try making your repairs yourself. However, for most of us, the risk of fire and the difficulty of finding the right parts makes this the time to call a professional.

Still More Reasons Your Gas Fireplace Keeps Going Out

  • Gas pressure. If your gas pressure is not set correctly, your fireplace will not work as it should. A certified technician will need to make the right adjustments.
  • Faulty gas valve.  Gas valve failure is rare, but when it happens, it is a fire hazard, and the valve should be replaced by a trained professional.
  • Moisture in the gas line.  This is also rare. Water and gas do not mix, so this could cause the flame to go out in your fireplace.
  • Blocked burner ports. Dirt, soot, and oxidation can buildup on burner ports, blocking gas flow to create the fire.

Routine maintenance can prevent most of the problems you might have with your gas fireplace. An annual cleaning is recommended.


Your gas fireplace usually keeps because of dirty or faulty sensors. In most cases, a simple cleaning of the oxy pilot, pilot light, and/or thermocouple or thermopile will solve the problem. In some cases, those parts may have to be replaced. Remember, working with gas can be hazardous. If you feel out of your depth, call a professional.