Water Heater Pilot Light Won’t Stay Lit: Common Causes and Fixes


When the water heater pilot light won’t stay lit, your home is out of hot water. In most cases, when you cannot get hot water, and you use a propane or natural gas water heater, it is highly likely that the pilot light is off. The pilot light refers to a small flame that ignites your water heater’s gas burner. The first thing you need to do when your water heater pilot won’t light is to relight it. There are directions in the water heater label on how to relight it.

If the water heater will not relight or keeps going off after relighting, then the heater might have a bad thermocouple. Other problems can cause the pilot light not to light, as explained below. In some cases, you might need to replace components of your water heating system, but in other cases, you will only need to clean the pilot light and other parts of the system.

Water Heater Pilot Light Won’t Stay Lit: Common Causes

Before you look at the following causes or try out any of the fixes provided in this article, ensure that you turn off the gas at least five minutes before the diagnostic. Turning off the gas earlier allows gas pressure to reduce and fumes to disperse. If you suspect there is a gas leak, besides an electronic ignition water heater that won’t light, call a professional and have them look at your whole system.

Some of the causes of water heater pilot light issues include:

 1. Thermostatic Control Issue

While it is rare, issues with the control valve can result in a water heater pilot that won’t light. Before you consider the control valve, you need to consider all other causes, and if they all strike out, check the control. A bad control valve only needs replacement to make the pilot light go on again. Before replacing, use a multimeter to test the functioning of the thermocouple – if the thermocouple is in good condition, then the next culprit will be the control valve.

  • What to do About It

The only way to correct a bad control valve is to replace it. Replacing a faulty main control valve is costly and needs a skilled professional to execute.

 2. Thermocouple Problem

When the thermocouple is faulty and the water heater pilot won’t light, you might need to replace the thermocouple. Simple damages on the thermocouple might mean that the sensor is bent away from the pilot light, or the thermocouple is completely broken.

In most cases, when the water heater pilot light won’t stay lit, the problem is with the thermocouple. As such, you need to test the thermocouple as your first part before testing other components of the water heater system. The unit is built to pick up an electric signal from the pilot’s heat to determine the status of the pilot.

The thermocouple can also get faulty due to dirt particles. When dirt gets in the unit, they block the signal making the thermocouple to interpret the pilot light has gone out. As a safety precaution, the thermocouple shuts off the gas supply when no signal is detected.

  • What to do About It

Before you start any diagnostics or repair, ensure that the thermocouple is cool to touch. Use fine-grit sandpaper to clean the surface of the unit to ensure that dirt is not blocking the signals.

If the unit still doesn’t work, you will need to examine it properly. The sensor at the tip of the unit should be in contact with the flame. If the sensor is bent away from the unlit pilot, gently press it back to its initial position. If the thermocouple is clean and shows no sign of damage, it needs to be tested with a multimeter. If the reading is less than 20MV, it is an indication that the thermocouple is broken and needs replacement.

If the electronic ignition water heater won’t light even after the repairs, you might need to replace it.

 3. Pilot Tube is Dirty

When dirt accumulates in the pilot tube, it obstructs the flow of gas. As a result, the water heater pilot light won’t stay lit since the pilot does not get enough fuel. If the unlit pilot won’t ignite at all, the pilot tube is likely blocked. Fortunately, a dirty pilot tube is the easiest to fix.

Again the flex tube that supplies gas via the gas controller might become kinked and interrupt the flow of gas. While this problem is not as common as a bad thermocouple, it can still cause a water heater pilot not to light.

  • What to do About It

To clean the pilot tube of dirt and debris, you need a needle. Insert a needle into the pilot hole and remove all debris. Since you are using a needle, the process might take longer and might need a couple of tries before the tube is successfully cleaned. After cleaning, light the pilot to test if it is in working condition. When the tube if fully cleared, the flame should be blue.

If the water heater pilot light won’t stay lit due to kinks in the fuel supply tube, unkink the hose to let gas flow freely.

Who to Call When Your Water Heater Pilot Won’t Light

When your electronic ignition water heater won’t light, you can perform several diagnostics to see what the problem is. If you cannot fix the problem, you will need a professional to diagnose and correct the issue. If your water heater pilot light won’t stay lit and you’re in the Phoenix, Arizona area, visit American Home Water & Air at 22047 N Black Canyon Hwy, Phoenix, AZ 85027, United States. You can reach them at (602) 993-0083.


All the above problems are easy to diagnose and correct. However, in some instances, the water heater pilot won’t light even after trying all remedies. In such cases, you need to call an expert. One extra tip: ensure that you test the system for gas leaks. Maybe the problem why the water heater pilot light won’t stay lit is because of insufficient gas reaching the pilot. To do that, use soapy water along the pipes to see where bubbles are produced.

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