Why does my pilot light keep turning off?

Author: Prof. Melissa Marquardt IV  |  Last update: Sunday, August 3, 2025

Gas Valve & Gas Supply Issues The pilot light depends on a reliable source of gas or propane in order to stay lit. Any issues with the gas valve that supplies that gas to the flame, whether it be dirty or malfunctioning, can result in that flame going out.

How do you fix a pilot light that won't stay on?

How To Re-Light A Furnace Pilot Light ?
  1. Step 1: Review Furnace Manual. ...
  2. Step 2: Identify Pilot Light. ...
  3. Step 3: Turn OFF Gas. ...
  4. Step 4: WAIT 5 Minutes, then Turn Gas to "Pilot" ...
  5. Step 5: Hold Reset Button. ...
  6. Step 6: Press The Igniter While Holding The Reset Button. ...
  7. Step 7: Turn Gas to "ON" position.

Why does my pilot light keep kicking off?

The issue could be: A dirty tube: If the pilot light tube is dirty, it can put out the light over time. You'll need to clean it with something abrasive to get it working again. Not enough gas: Sometimes, the gas valve will leak, or something else prevents gas from getting through the line.

Why does the pilot light on my gas fire keep going out?

The Fix: Pilot Light to Gas Fireplace Won't Stay Lit

This can be an indication that your fireplace thermocouple is either bad or worn out. However, if your pilot is lit but the gas fireplace isn't, then there's probably a problem with your thermopile.

How do you know if your thermocouple is bad on your furnace?

A working thermocouple will give a reading of between 25 and 30 millimeters. If the reading is less than 25 millimeters, it should be replaced.

TOP 10 Reasons Why the Gas Pilot Light Goes Out & Won't Stay Lit!

Will the pilot light go out if the thermocouple is bad?

The Pilot Lights But Won't Stay Lit

If the flame lights and goes out when you release the gas control knob after holding it in for the recommended 20 to 30 seconds, that's the sign of a thermocouple malfunction.

How much does it cost to replace a thermocouple on a furnace?

For those who prefer not to attempt a DIY repair, hiring an HVAC technician is a safer option. The cost for a professional furnace thermocouple replacement usually ranges from $80 to $150, depending on your location and the specific HVAC company. This price includes both the part and labor.

What causes the pilot light to go out on a gas furnace?

Thermocouple Malfunction

It is positioned very close to the flame, and when lit, the pilot light tells the thermocouple to keep the gas line open. A thermocouple that is dirty or malfunctioning will often shut off your gas supply in error, causing the pilot light to go out and your furnace to stop working.

How to clean a thermocouple on a gas heater?

How to Clean a Thermocouple
  1. Locate the pilot assembly and find the thermocouple. ...
  2. Use an adjustable wrench as needed to remove thermocouple from the gas valve.
  3. Detach the thermocouple from the pilot assembly. ...
  4. Gently scrub the thermocouple with the abrasive side of a sponge or scouring pad to remove the soot.

Why does my thermocouple keep going bad?

There are two main reasons why your thermocouple might fail. The first is age. For the most part, your thermocouple is more likely to fail once it takes on some wear and tear. Additionally, thermocouples can sometimes fail due to manufacturer defects.

What does a dirty thermocouple look like?

To figure out if your thermocouple is dirty, look at its tip. If you notice the tip is covered with a layer of soot, this means it needs to be cleaned as soon as possible. If you ignore this, you'll start having problems with the pilot light staying lit on a consistent basis.

Should I worry if the pilot light goes out?

Is It Dangerous if The Pilot Light Goes Out? The worry here is that when a pilot goes out, the gas valve that supplies the fuel for the pilot flame could still be pumping gas. This can mean a buildup of gas, and when the pilot is relit or relights itself, it could result in a very serious explosion.

Can a pilot light go on and off?

It shouldn't be able to re-light itself. It should have a bi-metal strip which prevents gas being delivered unless the pilot has heated the strip to sustain it on. If the pilot goes out regularly then the pilot flame is either being blown out or the bi-metal strip is faulty.

How to clean a pilot tube?

Take a soft brush such as an old toothbrush and gently remove any visible debris from the pilot orifice, flash tubes and ignitors. Next, insert a sewing needle or thin wire into the pilot orifice, the flash tubes and the holes in the ignitors, as well as in the burners, wiggling it gently to dislodge any debris.

How do you keep a pilot light on?

Keep the gas control knob held down for a further minute until the flame starts turning blue. Once you have released the knob, the pilot light will usually continue to burn, however, if it goes out again, the re-ignition hasn't worked and you should repeat the steps.

Why is my pilot light not staying lit?

Common reasons include a nearby draft, dirt buildup, or a malfunctioning thermocouple. Another pilot light drawback is energy waste. Since the pilot light needs to remain active, your furnace is always consuming some gas. It's not a lot—usually just a few therms of gas a month–but that obviously adds up over time.

How to clean a thermocouple without removing it?

Clean the thermocouple - using the emery cloth sandpaper, sand the ends of the thermocouple and then give it a finishing touch with the lint-free cloth. Hopefully, you can get to the ends of the thermocouple without having to detach it from the assembly, but you may have to do that.

Why does my gas heater keep shutting off?

Blockages in the Flue Pipe

Once the gas starts to build up, this may cause your heater to overheat and turn off early. If your furnace keeps shutting off after a couple of minutes, it may be necessary to work with a licensed professional to remove the blockages in your flue pipe and HVAC system.

Will a bad thermocouple cause pilot light to go out?

Faulty Thermocouple – If the pilot light goes out, it's up to the thermocouple to cut the gas off.

Will gas leak if pilot light is off furnace?

A gas-powered heater uses a pilot light to ignite the flame that heats your home. The pilot light is a small, continuous blue or yellow flame that is ignited by a spark from an igniter or thermocouple. When this flame goes out, it can cause the gas to leak from the burner and into your home.

How do I reset my furnace ignitor?

You can reset the ignition on your furnace simply. To do this you must cut the power to the furnace first by turning off the circuit that powers it. Once the power is off you can remove the burner door to reveal the ignitor. Turn this to “off” and leave it off for at least 5 minutes.

Can I replace a thermocouple myself?

It's easy to replace, and a new one costs $5 to $10. Rather than trying to unfasten the thermocouple inside the water heater's burning chamber, it's easier to remove the whole burner and thermocouple assembly.

What is the most expensive part to fix on a furnace?

A heat exchanger replacement is often one of the most costly repairs in a furnace, and the expense can sometimes rival that of installing a new furnace. Typical replacement costs vary widely but can easily reach several thousand dollars, especially if labor costs are factored in.

Why does my pilot light keep going out after replacing thermocouple?

Once you have replaced the thermocouple, turn on the furnace and check to see if the pilot light stays lit. If your pilot light doesn't stay lit, it may be due to something blocking the thermocouple. You can try cleaning or replacing it, but if that doesn't work, you may need to call a professional.

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