7 Reasons Your Water Heater's Pilot Light Won't Come On

Updated April 3, 2025

The water heater in your home is a lot like a huge kettle that heats the water and distributes it throughout the home when it is demanded. These huge “kettles” or hot water tanks comprise several essential components, including the pilot light. In this blog, we will discuss the role of a water heater pilot light and some top reasons why it wouldn’t light.

If you have a gas water heater not working as it should, read along to learn how to troubleshoot the issue.

What is a Water Heater Pilot Light?

Gas water heaters usually have a pilot light and a burner assembly that work together to heat the water. The entire work of the water heater begins when the pilot light, a small flame, ignites the burner and sets the whole unit into action.

The water heater pilot light has three main components, which include the thermocouple, gas valve, and pilot light assembly. Sometimes, a malfunction in one of these components leads to the water heater not heating the home’s water. Below is a summary of how this is caused.

Why The Pilot Light Won’t Light Up: Troubleshooting Tips

1. Residual Gas Inside the Unit

Residual gas inside the unit can often arrest its flame, causing it not to light the pilot. In turn, you will end up with a water heater that isn’t heating the water as needed. Here’s what you should do to troubleshoot this issue:

Turn off the gas supply to prevent more gas from therein the unit
Ventilate the area where the water heater is located by opening doors and windows.
Allow several minutes to an hour for the gas to disperse out of the unit.
When the gas has been ventilated, check for gas leaks by using a gas leak detector.
Look over the water heater for issues like damaged components, loose connections, or obstructions in the pilot light orifice.
Try to relight the pilot light after the extra gas has dispersed.

If clearing the leftover gas didn’t help you reignite the pilot light, you will need to call a professional water heater technician. It is also best to call a professional if you ever feel unsure about any of the suggested steps above.

2. Automatic Igniter Isn’t Working

Most pilot lights have an igniter button. This is similar to the automatic igniter on propane grills. When you press the button, it emits a small spark that ignites the gas and lights the pilot flame. The igniter often wears out and will no longer produce a spark when you press the button.

A faulty igniter is easy to diagnose as you should be able to see it spark every time the button is pressed. If you don’t see a spark, then you’ll need to use matches or a stick lighter to ignite the pilot instead. If the ignite button does not work, try one of the following steps:

Clean the igniter with a soft brush, removing dirt, dust, or debris. Be sure to turn the gas supply off before doing so.
If your water heater comes with a battery, try replacing it. The battery can be found near the ignite button.
Check the electrical connections to ensure everything is connected properly. Tighten any loose connections if needed.
Replace the igniter with a new, compatible one.

When in doubt, call a water heater technician for assistance.

3. Pilot Tube Is Clogged

In many cases, the reason that you can’t get your pilot light to ignite is that the pilot tube is clogged. This is a small metal tube that supplies the gas needed to ignite the pilot and keep it lit. Over time, the pilot tube becomes clogged with debris, which will prevent gas from flowing to the pilot light. Without the gas flowing correctly, relighting the pilot will be impossible.

How to Clean the Pilot Tube

Turn off the gas supply and the water heater
Access the pilot assembly by removing the panel covering and locating the pilot tube.
Disconnect the pilot tube and clean it with a pipe cleaner.
Check the pilot orifice for damage and ensure that it is clear.
Reassemble the pilot light assembly, ensuring all the connections are secure.

If you cleaned the pilot tube but the water heater won’t light or stay lit, you will need to contact a professional who can address the issue for you.

4. Flex Gas Tube Is Damaged or Kinked

The flex tube connects your main burner to the water heater, supplying gas to the burner and the pilot light. If the flex tube is kinked or damaged, it can prevent gas from flowing as it should. While some gas will still likely flow into the unit, it generally won’t be enough for it to work properly. As a result, you won’t be getting the hot water you’re counting on and will likely get cold water in the shower.

Luckily, this is extremely easy to spot. If you see that the gas tube is kinked, you will want to call a professional plumber to repair or replace it. This is not something you should attempt to fix on your own as you could further damage the tube and potentially cause it to leak.

5. Thermocouple Is Dirty or Obstructed

The role of the thermocouple is to control the gas flow into the unit. When it detects the pilot flame, it opens up the valve to allow gas to flow into the unit. If the pilot light goes out, the thermocouple will detect that there is no flame and automatically close the valve to shut off the gas flow.

Over time, the thermocouple can become covered in dirt and grime. When this happens, it can prevent it from properly detecting when the pilot light is lit. As a result, the water heater pilot won’t stay lit.

Cleaning the Thermocouple

Turn off the gas supply and the water heater
Access the thermocouple by removing the covering to the burner assembly.
Locate the thermocouple, disconnect it, and clean it with sandpaper or steel wool. Be sure to be gentle with your motions as this part of the water heater is very fragile.
Check the thermocouple for any damage and notify your technician if you find any damage.
Reconnect the thermocouple and replace the access panel, turning the gas supply and water heater back on.

6. Thermocouple Is Faulty or Damaged

When the pilot is lit, the thermocouple should basically touch the flame. If it is damaged, it won’t work properly to help the pilot detect the flame. Look for any of these signs of damage in the thermocouple:

Cracks or breaks
Corrosion or rust
Burn marks or soot
The bent or warped anode rod
Loose connections
The pilot light won’t stay lit

If there are no signs of damage, there is a good chance that the thermocouple is faulty. Thermocouples can wear out with age. When this happens, it will need to be replaced before the water heater will be able to work again. This is a fairly simple repair, but it is still something that is best left to the professionals.

A plumber will be able to test whether the thermocouple is working using a multimeter. When the thermocouple is working properly, it will carry a small electrical charge. If the multimeter doesn’t detect a charge, then this indicates that the thermocouple needs to be replaced.

7. Control Valve Is Worn-Out

If the thermocouple isn’t the problem, then most likely it means that the pilot control valve is worn out. This component of the water heater houses the pilot control knob and is what allows you to control the gas flow and turn the pilot light on.

Signs of a Worn Our Control Valve

The water heater lights up but won’t stay lit
Inconsistent water temperature or inability to reach desired temperature
No hot water
The water heater is producing weird noises
There is a gas smell
There is visible damage such as corrosion or wear on the the control valve

If the main control valve goes out, the only solution is to hire a professional to have it replaced. This job is a bit more costly and time-consuming than the other fixes, but it is still preferred over having to replace the entire unit.

3 EXTRA WATER HEATER PILOT LIGHT TIPS

8. Low Gas Pressure

Obviously, gas is a key player in a water heater as it helps ignite and sustain the pilot light. When there are low levels of gas pressure, there could be issues with the either the gas supply or its regulator. There are a handful of things you can to diagnose and address these issues.

If you have other gas appliances in the house, check them to see if they are having gas supply issues as well.
Inspect the gas regulator on your water heater for any damage.
Check the gas meter for any damage or faulty operation. Be sure that the gas valve at the meter is completely open.
Test the unit for gas leaks.

If you notice damage to the gas meter or any gas leaks, you must contact the gas company immediately. If there are issues with the condition of the gas lines or the water heater, you will need to contact a plumber or a professional water heater technician immediately.

9. Draft or Air Flow Issues

Another reason for the gas hot water heater not working is the presence of a draft or airflow issues. This is especially true if you find that the water heater pilot light won’t stay lit. Any wind blowing through the area where the water heater is located can cause the pilot light to go out as quickly as you turn the gas knob on. Here’s what you can do about those drafts:

Seal any gaps and cracking using caulk or weatherstripping materials
Install a draft diverter
Move the water heater to a better location where there are minimal drafts
Install a flue vent cap
Use a pilot light shield to protect it from drafts
Ensure proper ventilation in the area
Install a wind guard around the exterior vent pipe to reduce the impact of wind gusts
Make sure the venting system is free of obstructions and is properly installed

Your best bet for addressing excessive draft issues around your gas water heater is to get a professional involved. Contact us today for a quick resolution to your issue.

10. Old or Worn-Out Water Heater

Lastly, any problems with the pilot burner or light working properly can simply be an issue of an old or worn-out water heater. The typical lifespan of a gas hot water heater is normally between 8 to 12 years, depending on maintenance and installation quality. If your water heater has served out its lifespan, it may be time to replace it and avoid future problems with getting the desired temperature or hot water in your home.

Professional Water Heater and Plumbing Services

If you’re having issues getting your pilot light to stay lit or any other troubles with your water heater, the team at Apex Plumbing, Heating, and Air Pros is here to help. Our licensed plumbers work on all makes and models of tankless water heaters and traditional water heaters. If your water heater isn’t working for any reason, we can quickly diagnose the problem and determine the best repair for your water heater correctly the first time..

If the issue cannot be fixed, we also specialize in water heater replacement and installation. Our team also specializes in a full range of other residential and commercial plumbing services for residents of Columbus and the surrounding areas. To schedule an appointment to have your water heater serviced or inspected, give us a call today.

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FAQ: Gas Water Heater

How do water heaters work?

Using a gas burner assembly or electric element, water heaters heat cold water and store it in its insulated tank until it is needed. All water heaters are equipped with thermostats which regulate water temperature and ensure that the hot water supply is consistent throughout the home.

Why would the water heater pilot light go out?

The water heater pilot light is often caused to go out by a faulty thermocouple, drafts, dirty pilot tubes, low gas pressure, worn-out control valve, or a broken igniter.

Why won’t my pilot light heater turn on?

The pilot light heater will have trouble turning on if the unit has a faulty thermocouple, clogged pilot tube, low gas pressure, malfunctioning gas valve, or drafts that can blow out the flame.

How do you clean a thermocouple on a water heater?

To clean the thermocouple, turn off the gas and the water heater. Remove the thermocouple and gently clean it using fine-grit sandpaper or steel wool. Wipe it clean and reattach it back to its spot.

How do I unclog a pilot tube?

To unclog a pilot tube, turn off the gas and the water heater. Then, remove the covering and remove the pilot tube. Using a pipe cleaner or compressed air, clear any debris or obstructions. Reattach the pilot tube back to its spot and restart the water heater.

Why is my gas not getting to the pilot light?

The gas may not be reaching the pilot light due to a closed gas valve, clogged pilot tube, faulty gas control valve, or low gas pressure.

How do I turn my water heater pilot back on?

Locate the gas valve turn it to “pilot” and hold it down for 30 seconds or until the flame stays lit.