Reliance 606 Water Heater Pilot Won’t Stay Lit [5 Easy Solutions]

The pilot on your reliance 606 water heater ignites the gas provided to the heater to produce heat. Needless to say, if the pilot doesn’t lit properly you won’t be getting any hot water.

It’s common for a pilot light to go out once in a while but if the issue persists, then you should look for the cause of the problem.

We are here to help you with just that. If your reliance 606 water heater pilot won’t stay lit, the common reasons behind it are air in the gas line, faulty thermocouple, defective gas supply, bad igniter, and tripped TCO.  

Why Reliance 606 Water Heater Pilot Won’t Stay Lit [5 Easy Solutions]

Now, we’ll cover all these common reasons behind your water heater pilot won’t stay lit and their simple solutions. Some of the problems are easier to solve than others.

Read every possible cause and how you can solve them carefully to fix your water heater and get the hot water running again.

1. Air In The Gas Line

If there is air in the gas line, the heater pilot won’t light up properly.


To check this issue you have to bleed the air from the gas line. Here are the steps to bleed the air from the gas line of your water heater.

  1. Begin by turning the water heater off. Shut off the gas valve and the pilot light. 
  2. Touch the tank to see if it’s cool. If not, wait for the water inside to cool down.
  3. Find the drain cock or hose bib. It will most likely be located at the bottom of the water heater.
  4. Place plastic under the hose bib to protect your floor from getting wet.
  5. Now, attach the hose to the hose bib. Turn the hose clockwise to thread it to the hose bib.
  6. Drain the water into a tub or out into your lawn.
  7. There is a valve on the top of the hose bib. Open it. Allowing the tank to drain, check for sputtering noises. If you can hear such sounds, it means there is gas inside the tank.
  8. The water coming out at first will look red and rusty. As you keep draining it, fresh and cold water will start coming out. When the water is completely clear, turn off the valve that is on the drain cock. 
  9. You can turn the heater on at this point.

2. Defective Thermocouple

A defect in your Reliance 606 water heater thermocouple can cause the pilot not to ignite properly. You can check if the thermocouple is what’s causing the issue with the help of a multimeter. For that, the thermocouple first needs to be separated. 


Here are the steps for Reliance 606 water heater thermocouple replacement and testing:

  1. You’ll need only a screwdriver to carry out the removal of the heater thermocouple. First, turn off the gas supply by shutting off the valve. 
  2. Make sure that the thermostat is turned as low as possible and the gas control knob is in the OFF position.
  3. There is an outer door and two screws that hold the manifold door assembly. You’ll need to remove them.
  4. The pilot tube, thermocouple, and other heater parts are ready to be dismantled from the gas control valve. 
  5. Remove the burner assembly from the gas combustion chamber.
  6. Remove the wire connector that can be found in the manifold door. You can do that by unclipping the retainer clip.
  7. Now, by removing the two screws that hold the burner in place, you can take the thermocouple out of the pilot assembly.
  8. With the thermocouple separated, you can test it with a multimeter. Put one end of the multimeter to the copper body of the thermocouple and the other end to the place where the thermocouple connects to the valve. 
  9. Light the pilot. If the reading on the meter doesn’t show 12mV or more after waiting for about a minute, your thermocouple is broken. If your thermocouple is broken, you’ll need a new one to replace it. 
  10. After testing, to put the thermocouple back in its place or install a new one, you have to reverse what you did while removing it. 

3. Issue With Gas Supply

No gas, low gas pressure, or, dirt in the gas line can cause your pilot to malfunctioning.


Contact your gas utility company to fix these issues.

4. Defective Igniter or Electrode

Issues with the ignitor are another reason why the Reliance water heater pilot may not stay lit.


You’ll need to replace your ignitor with a new heater igniter. These are the quick steps to replace your ignitor- 

  1. Begin by unplugging the power cord and turning off the gas supply.
  2. Remove the cover from the burner. You’ll have to loosen the mounting nuts that secure the cover in place with a socket. 
  3. The burner tube is secured to the control valve with a nut. Unscrew that.
  4. Now, the igniter and sensor wire harness may be disconnected from the valve.
  5. Pull the burner assembly off after removing the vapor sensor and bracket from the base of the tank.
  6. Remove wires from the vapor sensor.
  7. Pull the igniter and flame sensor along with the old elements free after removing the screws holding them in place.
  8. Release the burner tube by pushing it through the cover.
  9. From the burner cover, peel off the old insulation and replace it with the new one.
  10.  After inserting the burner tube and gasket through the cover to secure the gasket into place, insert the new igniter on the burning tube bracket. 
  11. Replace everything carefully.

By following our guide you can replace your Reliance 606 water heater igniter in no time and fix your pilot light. However, if you don’t have any experience with a water heater and don’t feel confident about doing it yourself, it is best to call in a professional.

5. Tripped or Broken TCO

The TCO or Thermal Cut-Off switch is designed to turn off the gas supply if the water heater faces high combustion temperatures which can be a result of poor combustion or flammable vapor, or inadequate combustible air supply. 

If it trips or breaks, the pilot won’t stay lit.


If the TCO has tripped all you need to do is reset it and the pilot will be fixed and stay lit. But after resetting the TCO, if the pilot doesn’t stay lit, you’ll need to replace the TCO.

The TCO trips when there is a shortage of combustible air. When this happens, after reattaching the wire leads, you have to press your heater reset button which is located on the side of the heater body.

To replace the Thermal Cut Off switch, remove the screws securing the thermal switch in place. Remove the TCO switch and align the new one in its place. Now, reattach the screws. Reconnect the two wires and make sure the connection is tight. 


How do I know if my gas water heater thermostat is bad?

Ans: If cold water comes out of the hot water tap then your upper thermostat is broken. But if initially, hot water comes out and then cold, your lower thermostat is damaged. 

Can you replace the thermostat on a gas hot water heater?

Ans: You’ll have to replace the entire gas valve as the thermostat cannot be separated from it.

How much does it cost to replace a thermocouple?

Ans: It will most likely cost you  $150 to $250.

How long do thermocouples last?

Ans: It can last for years. Make sure to test it after every four years to ensure that it has a long life.

Does gas still flow when the pilot light goes out?

Ans: If the flame sensor is broken, in that case, gas will keep flowing even if the pilot isn’t lit. So you should always be careful about that and turn off the gas supply when the pilot light is malfunctioning. 


Now that you know why your Reliance 606 water heater pilot won’t stay lit, you can solve the issue and get a constant supply of hot water.

Hopefully, our comprehensive guide is enough to solve your issues but if you have more questions you can always comment below. We’ll be happy to help you out.

About William

William is the founder of He has real life practical skills in fixing smoker & heating appliance issues. He loves to share his knowledge & helps others in fixing their appliances & saving their money. William firmly believes that anyone can repair his or her unit with the correct guidance & knowledge. See more at about us.

2 thoughts on “Reliance 606 Water Heater Pilot Won’t Stay Lit [5 Easy Solutions]”

  1. We have replaced as of yesterday the 4th pilot assembly and also igniter switch. Since 2009.
    Frustrating ….. we thought it was fixed but it still goes out.
    What would be possibly the next thing we should try ? We’ve done 2 of the 5 .
    Please help! Financially we aren’t in a position to buy a new hot water heater. We have 3 grandchildren and our son living with us. Help!!!

    • Hi Karen

      Don’t be frustrated. Every problem is solvable.

      Well, your reliance 606 water heater pilot won’t stay lit due to one or more reasons like air in the gas line, faulty thermocouple, defective gas supply, bad igniter, and tripped TCO.

      First, try to detect the main reason behind the issue & fix it accordingly following our solution guide in the article.

      Hopefully, you can find out & solve your problem.

      Wish you good health & best of luck.


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