5 Reasons Why Your Water Heater Pilot Light Won’t Stay Lit

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The pilot light in your hot water heater does more than simply ignite the gas. Without it, the water heater won’t be able to maintain internal temperatures, allowing the water to cool off. Pilot light issues are some of the most common problems experienced with gas water heaters.

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This means it can be a nightmare when your water heater pilot light won’t stay lit. In some cases, it could also be an indicator of potential gas buildup.

Here are the top five reasons your pilot won’t stay on, as well as methods to fix each issue.

Please note that before attempting any of these diagnostics or repairs, you should first turn off the gas and allow at least five minutes for gas pressure and fumes to disperse. This is a good rule of thumb for relighting the pilot in general, not just for diagnostics purposes.

Reason 1: Dirty Pilot Tube

dirty pilot tube

Dirt and debris can collect in the pilot tube, causing the flow of gas to be blocked. As a result, the pilot doesn’t get enough fuel to stay lit. This is also a likely cause if the pilot won’t ignite at all. Thankfully, a dirty pilot tube is the easiest issue to fix.

How to Fix

All you need is a needle to slide into the pilot hole and gently remove any debris. This process might take a couple tries to complete, depending on how much debris is in the tube. Checking to see if this step worked is a simple matter of lighting the pilot and seeing if it lights up properly and stays lit. A healthy flame will be blue in color.

Reason 2: Kink in the Flex Tube

kinked water heater flex tube

The flex tube provides fuel via the gas controller. On occasion, the tube can become kinked, interrupting the flow of gas.

This is one of the most common reasons the burner won’t stay lit, even when the pilot seems to be in working order. While not as common as thermocouple issues, it’s an easy fix and should thus be rules out early on.

How to Fix

Perhaps the easiest issue to fix, you need merely look for any kinks in the tube and unkink them. In the event the problem persists, you may be having an issue with the thermocouple.

Reason 3: Obstruction in the Thermocouple

damaged thermocouple

Thermocouple problems can be fairly common, and this component is often the culprit when the water heater pilot keeps going out. This device is designed to pick up an electrical signal from the pilot light’s heat to determine whether or not the pilot is on.

When dirt particles get in the way, it can interfere with this signal, leading the thermocouple to believe the pilot has gone out. It then shuts off the gas supply as a safety precaution.

How to Fix

Ensure the thermocouple is cool to the touch. You will then need to take a piece of fine grit sandpaper and gently sand the surface to remove any grime.

This should ensure the component is working properly. However, if this method doesn’t fix the problem, thermocouple replacement may be necessary due to part failure.

Reason 4: Damaged Thermocouple

This is a more severe scenario, as it may require replacing the part. Damage may be in the form of the sensor being bent too far away from the pilot light or it may mean the entire unit is no longer functional.

How to Fix

Examine the thermocouple. The sensor at the end should lightly touch the flame when the pilot’s lit. In the event it has become bent away from the flame, gently bend it back.

A thermocouple which shows no signs of damage and is clean should be tested with a multimeter. The reading should be above 20MV. Any reading below this is a clear sign that the thermocouple itself is damaged and needs to be replaced.

Reason 5: Main Control Valve

how to light pilot light1

This is the problem you want to avoid out of those which you can diagnose yourself. The easiest way to diagnose a bad control valve is to try all other solutions first.

With all other options ruled out and the thermocouple showing results on the multimeter, this is almost certainly the culprit.

How to Fix

There is only one way to fix a bad control valve and that is to replace it. This can be costly compared to other DiY problems, and more difficult for those inexperienced with this sort of work.

When All Else Fails

pilot keeps going out

All of the above mentioned causes can be diagnosed and remedied by the average homeowner. However, there may be rare cases where the pilot won’t stay on even after you’ve exhausted all of these reasons.

In such extreme cases, the only solution is to call in an expert to examine the water heater fully. Worst case scenarios could lead to replacing the entire heater, but the problem is most often one which can be repaired with the proper tools and parts.


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  1. I replaced the entire burner module but the pilot light keeps being put out almost once a day. What is the next step to fix this problem. Appreciate any help from professional out there.

    • We’re in the same boat. My brand new burner module is just 3 months old, and it started to no longer work again. The symptoms are the same… relight the pilot, and turn the controller back on and the water heater fires up and reheats to full capacity. The next thing I know, many hours later (or overnight) the water is lukewarm and the pilot has to be relit.

      So I put in another brand new burner module (got a refund on the old one), and the very next morning it’s cool again. I had to relight the pilot. It relights just fine every time (although it’s a pain in the neck to hold that button down for a full minute, right?).

      At this point, it has to be the controller. It’s not the supply… the thing heats up with no issues. Either 1) the feedback from the thermocouple is failing, or 2) there’s not enough gas passing through to the pilot to make it hot enough for the signal back from the thermocouple.

      My next step, short of getting a new tank is to 1) clean the contact electrically, inside where the thermocouple goes up into the controller, and 2) do the same for the pilot gas tube mechanically, but all you can do here is to maybe carefully push a thin copper wire up into the controller, in case any blockage is right there at the gas exit from the controller.

      Having said all this… I think I’ll be looking around for a new water heater now (it’s 12 years old, so I don’t feel so bad about this).

  2. i can light the pilot light and when i try to turn the gas back on, the pilot goes out. There is gas flow to the other appliances in the house.

  3. Got up this morning to no hot water, went out and noticed that the pilot light was out. Yesterday everything was fine. Why did it just all of a sudden go out.

    • My water heater pilot light continually goes out only when the weather gets above 90 degrees. This problem only occurs in the summer. It stays lit in the winter. Any ideas on what causes the issue and how to fix it?

      • This is often a ventilation issue. If it gets too hot, the pressure can increase and actually put out the flame. This is more common with water heaters located in attics. Make sure to clear/clean out around the water heater or any nearby vents to the exterior so it can “breathe” a bit better.

  4. Try cleaning the vent underneath the water heater. They get dirty with dust and wont allow the air to supply the gas flame.

  5. Sometimes, I encountered a problem that the light RV water heater pilot didn’t work and this is so bad to me. I think your ways are pretty easy to do and I am gonna try them.

  6. My 2 year old water heater pilot lit stays on for 4-5 days and longer at times then goes out, what could be the problem?

  7. Hey all I just had a good win with my water heater I thought I’d share.

    Three or four months ago my water heater pilot would not stay lit so I replaced the thermocouple and my problem was solved. Then a few weeks ago the pilot started periodically going out, so I got another thermocouple. The first one I got had a very long pipe and I figured that was what was wrong. But it got worse with the new one; it would go out after every tank heated. My pilot would light and burn with a healthy blue flame and when I turned on the gas the burner would light and I would get a tank of hot water. But when I would go back to look at it later, the pilot would be out.

    So I watched a few videos and decided to try two things. First I disconnected the pilot tube from the control valve and blew compressed air through it to be sure it was clear. Then I unscrewed the new thermocouple at the control valve and put it back finger tight plus a quarter turn. I had put it on very tightly.

    I am not sure which fixed it but my pilot stays on now!

  8. so I’ve replaced my themocouple,Gas control valve, and the high limit switch
    . Nothing has fixed the problem. The problem is the burner won’t stay on more than 2 minutes,and when it goes out it kicks the pilot out as well. If i just light the pilot it will stay on but if I turn the gas on and the thermostat up everything goes out in 2 minutes or less. any ideas? I hope I don’t have to buy a new water heater

  9. So I had a hot water tank that would not stay lit for more than a month. Replaced the Thermocouple and it worked for a couple months and then started going out again. Replaced the hot water tank and it worked for a day and went out again. Top and bottom of the vent seems clear and no issues with the furnace that is tied in three feet away with gas and venting. Willing to try anything at this point. Suggestions?

    • If you are on propane by chance make sure your water column is set right at the regulator, that was a problem I had in the past, a call to your provider and they will send a tech out to check it for you.


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