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

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.
Note: This post may contain affiliate links. This means that at no cost to you, we may receive a small commission for made purchases.

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

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.


author avatar
Anthony Barnes
Anthony Barnes is the founder of Water Heater Hub and a second-generation plumber by profession. Before developing Water Heater Hub, Anthony Barnes was a full-time plumber, and he has undertaken a wide variety of projects over the decades. As a second-generation plumber, it was easy for Anthony to get used to the technicalities of all from a tender age


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