6 Reasons Why Your Water Heater Pilot Won’t Stay Lit

Are you frustrated because the water heater pilot light won't stay lit? This is not only irritating but troublesome as well. The unlit pilot light can turn your comforting hot morning shower into a nightmare. After all, having a shower with not-so-warm water is the least that you would expect at the start of the day!

There could be numerous reasons as to why the pilot lights have gone out of order in your water heater. However, if you could understand the weirdness behind the unlit pilot light, then you will be able to prevent such a situation in future.


In this article, we are going to discuss the six probable reasons that might lead to an out-of-order pilot light. And further, how you can fix it. Without beating around the bush, let's begin with our list.

#1 Thermocouple is dirty


The majority of the water heaters that are present at homes today are based on a thermocouple which heats the water when turned on. This particular device is the central object to the operation of a water heater.

A thermocouple indicates you if the pilot light is switched off or on. It does so with the help of an electric current which is generated by the pilot’s heat. However, as a part of safety precaution, thermocouple turns off the supply of gas whenever it detects the unlit pilot light.

​However, if indeed the thermocouple is dirty, then the electric current flowing from the pilot may be impacted, leading towards the gas outage. You can fix this simply with the help of sandpaper. As a safety precaution, always remember to make sure that the supply of gas is turned off, and that the thermocouple is cool enough for you to touch it.

​#2 Thermocouple has bent

​Do you think dirt is the only danger to your thermocouple? Well no! A bent thermocouple is just as useless as a dirty thermocouple. It might be the reason as to why your water heater pilot light won’t stay lit.

When there is a bent in the thermocouple, it might stop working. The bottom line here is to diagnose how far away the thermocouple is bent as compared to the location of pilot light. If thermocouple is far away from the pilot, in that case, your thermocouple won’t be able to sense any heat. Simply follow the safety procedure mentioned in step 1, and get started with a DIY procedure.

​Try and bring the thermocouple back to its native position. You need to make sure that the thermocouple is close enough to the pilot. Also, ensure that the light is coming close to the sensor. Further, you should remember that a working pilot light glows in blue color. If this is what you have achieved, your water heater is ready to go!

​#3 Thermocouple is damaged

​If at this point of time, you are absolutely certain that it is the thermocouple which is the source of all problems. If there are no signs of bending or dirt, then this might indicate a broken thermocouple. The corrective measure here would be to either to get it repaired or alternatively, replace your thermocouple.

​Again, follow the safety procedures mentioned in step 1. Make sure that there is no supply of gas and the thermocouple is not hot. Further, just to be sure enough that the thermocouple is faulty. Then, use a multimeter to measure the voltage that is provided by the thermocouple to determine its usability. If the reading shows 20 MV or less then it means that the thermocouple is not usable at all.

How To Fix Water Heater By Testing Thermocouple

​#4 Pilot tube is dirty

Pilot Tube

​If it is not the thermocouple, then the pilot tube might be the source of all problems. The dirt that builds up in the pipe blocks the flow of the gas inside the water heater. However, the good news is that fixing this particular issue is easy and pretty much straight forward.

Once you have turned off the gas and ensured that the pilot to cool, simply make use of a needle to clean the tube inside-out.

​You need to make sure that you expel everything which is big enough and might be obstructing the path of the pilot. Once you are done with your cleaning just turn on everything and see if the pilot works right again. If it again fails to glow, you need to follow the entire process again until you are sure that everything is totally cleaned.

​#5 Flex tube is at fault

Flex Tube

​Well, this might be another reason behind the unlit pilot light. The flex tube connects the gas controller and it ensures that there is a steady flow of gas. However, at times, it happens that gas tubing is off placed, and thereby prevents the proper operation of the heater.

​If this is preventing your pilot light to stay lit, it is highly recommended to unkink the tube in order to resolve the issue. If this does not work then you need to install a new tube. However, it should be noted that this happens very rarely and should be given a try only when you have tried all the above-mentioned reasons and everything seems to be fine till now.

​#6 The main control valve has gone out

Main Valve Control

​There are certain rare cases where the issue might be in the main control valve. This might be the reason which is not allowing the pilot light on your water heater to stay lit. Generally, the control valves do not malfunction, and therefore you should be 100% percent sure that you have thoroughly checked other issues.

​If it is indeed the main control valve which is causing the problem, then it is highly recommended to get it replaced. However, if you are uncertain and are not sure about the main control valves, then please do check the thermocouple’s voltage with the help of a multimeter to arrive at a conclusion.

​Wrapping Up

​We hope that the above-mentioned probable causes would have given you a reason as to why your pilot light is behaving weird and is not staying lit.

Needless to say, it is difficult and frustrating to experience such issues in your bathroom especially when you’re already running late and can’t afford to invest an hour in solving such niggling issues. However, this list of tips would definitely save your day and keep you safe for the future.

​Do you have any recommendations regarding anything that you want to let us know? How has the list helped you to solve your issues? Do let us know through the comments section below. We would love to listen to your experiences.

Abigail Jones

Hi, I'm Abigail. I like spending time tearing my house apart and putting it together back again. Join me on home improvement tutorials, tips on my blog.

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