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How To Fix A Pilot Light On A Gas Furnace That Will Not Stay Lit

The pilot light in your gas furnace supplies heat to your home. An operational pilot light in your furnace means safety from the possibility of a gas leak. If the pilot light will not stay lit, it needs to be fixed ASAP to supply heat to your home and for safety reasons. There are numerous things that may make the pilot light on your furnace to not stay lit. Below we will give you the most probable and easiest ways to fix your pilot light so it will stay lit and continue supplying heat to your house.

Pilot Light On Gas Furnace That Will Not Stay LitPilot Light On Gas Furnace That Will Not Stay Lit – How To Fix

We will show you step-by-step what to check on your gas furnace to help you get the pilot light to stay lit…

Step 1 – Open Up Your Gas Furnace:
(You will be checking the pilot tube and thermocouple to find out what may be the issue)

  1. First turn off the pilot light on your furnace.
  2. Turn off the gas flowing to the furnace using the shutoff valve.
  3. Let your furnace cool down for 30 minutes. This needs to be done so it is not hot and is safe to open.
  4. Open the cover that covers the pilot light and visually inspect inside.

Step 2 – Visually Inspect The Thermocouple For Alignment And Bends:
The function of the thermocouple in your gas furnace is to check to see if the pilot light is ON or OFF. The thermocouple detects the pilot light as it can sense the heat the pilot light creates. When the thermocouple detects the pilot light is OFF it will shut down the gas flow. This is all done as a safety feature so there are no gas leaks. If you have a malfunctioning thermocouple, it can shut OFF the pilot light even when it is supposed to be ON. A bent thermocouple will cause it to not be properly aligned or “in place”. This makes it so it is not able to detect the heat of the pilot light. If bent, the thermocouple cannot operate properly. When your pilot light will not stay lit for more than a few moments, turn the pilot light ON and be sure it is aimed at the thermocouple. If the pilot light is not aimed correctly, simply bend the thermocouple to line it up with the pilot tube. Be sure everything has cooled down before realigning the thermocouple and pilot light.

Thermocouple and pilot tube burner in gas furnaceThermocouple and pilot tube burner in gas furnace

Step 3 – Clean Dirty Thermocouple:
If the thermocouple is NOT bent and is aligned correctly, you may have a clogged or dirty thermocouple. If your thermocouple is dirty, get some fine grain sandpaper and clean it off. This should clean the thermocouple and get it to operate properly therefore getting the pilot light to stay lit and to supply heat to your home.

Gas furnace thermocouple pilot light locationGas furnace thermocouple and pilot light location

Step 4 – Visually Inspect The Pilot Tube (Burner):
The pilot light may be going out if the pilot tube (burner) is blocked, dirty, or clogged. A dirty pilot tube will not be as reliable than if it is clean. A dirty pilot tube may be causing your pilot light issues. It is difficult to determine if the pilot tube is clogged or dirty as it is almost impossible to see inside of it. Since it may be clogged, you can try cleaning it when your gas furnace has cooled down and the gas supply has been turned off. All you will need to clean the pilot tube is a needle. Get a needle and scrape the inside of the pilot tube. Any blockage in the pilot tube will cause the furnace to not stay lit. So cleaning it is an easy solution without having to replace any parts. Once cleaned out, put everything back in place and test out the furnace.

You may need to replace the thermocouple on your gas furnace.

Here is a video for how to replace the thermo couple on a gas furnace.

Video: How To Light A Pilot Light On Gas Heater (Furnace)

Here is how to light the pilot light on a gas heater

  1. Lighting the pilot light on a gas heater is simple to do.
  2. Turn the thermostat to its lowest setting.
  3. Turn the gas knob to the OFF setting and wait 5 minutes to clear out any gas.
  4. If you smell gas, don’t continue to light the gas heater and call a professional heater repair person.
  5. Locate the the pilot so you will know where to put the fire when it is time to light the gas heater.
  6. Turn the gas knob to the pilot setting, press it in and hold it, light the pilot while holding the gas knob down for a minute.
  7. Release the gas knob and turn it to the ON position.
  8. To make sure the gas heater is working properly, turn up the thermostat and see if the heater heats up.

Gas furnace parts location and identificationGas furnace parts location and identification

gas furnace replacement partsIf you need to replace parts on your gas furnace, here are gas furnace parts
that will fix your furnace once you can identify which part needs replaced.

These are simple fixes for a gas furnace that has a pilot light that will not stay lit. There are other ways to fix your gas furnace besides the simple methods above. These methods have been chosen as they are the easiest to perform and cost you no money. If your pilot light will not stay lit and you have tried the above methods, please leave a comment below and we can assist you with further troubleshooting.

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7 thoughts on “How To Fix A Pilot Light On A Gas Furnace That Will Not Stay Lit”

  1. Patricia A Grant

    My pilot light button on my Lennox 1983 G12 D2-82-4 furnace will not turn and depress.
    Water from the central air unit line got into my furnace and now the button is stuck.
    Can I use WD-40 to unstick the button so that it will turn from on off and pilot?

  2. My husband replaced the thermonucouple and the gas valve we can light the pilot and it will fire but as soon as its satisfied and turns off the pilot light goes off can you please give me some input

  3. If my pilot flame is too big and burns my thermalcoupling could it be a problem with the pilot or gas valve

  4. Hello,

    I have an older Mor-Sun Model RF-22 downflow gas furnace, with what is being called a Flat 750 Millivolt Thermopile or Powerpile. It simply looks like a flat piece of metal about 1″ wide x 2″ long. The general consensus seems to be that it is bad, causing the pilot to not remain lit. No one has been able to source a replacement Powerpile.
    Cannot a 750 ML wand type unit which seems to have the same two connection wires be retrofitted in front of the pilot light? Short of that I am being told $10,000 to replace the entire gas furnace. Appreciate any input you can provide. Thankyou

  5. Was the gas valve the issue for you? I have replaced the thermocouple, cleaned under the hood and replaced everything, but now the pilot won’t light at all even though I can hear gas coming out. When I pulled it all out before to clean (before replacing thermocouple) and put it back together it stayed lit until we turned the thermostat on, then the pilot went out. Now it won’t light at all

  6. DIY Project Help Tips

    Yes if you have replaced the thermocouple and the transformer but the pilot still won’t stay ignited, check the gas valve itself.

  7. I have replaced the thermocouple and the transformer but the pilot still won’t stay ignited no matter how long I hold the button.
    The thermocouple is in the flame good too.
    Any ideas?
    Could it be a bad gas valve?

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