Rheem Water Heater Failed Ignition Lockout

Rheem Water Heater Failed Ignition Lockout [A Troubleshooting Guide]

This is a complete troubleshooting guide on Rheem Water Heater Failed Ignition Lockout. In this article, what I am going to discuss: 

  • 7 possible reasons that get your Rheem water heater into the ignition lockout condition
  • The remedies to those culprits that activate the ignition lockout condition.
  • How to get the Rheem water heater out of the ignition lockout?

So, let’s get started right here. 

Table of Contents

Rheem Water Heater Failed Ignition Lockout [ 7 Reasons & Solutions]

Error code ‘Ignition Lockout’ on your Rheem Water Heater will pop up if you fail to establish burner ignition after three successive attempts. Several reasons like corroded burner ground wire, unplugged connectors, defective flame probe, and faulty gas valve cause the ignition lockout issue. 

Reasons of Rheem Water Heater Failed Ignition Lockout

Below, I will discuss all possible causes of ignition lockout conditions and their remedy. So, keep scrolling.  

01. Broken or Corroded Burner Ground Wire

Damaged or corroded burner ground wire is one of the leading causes behind the failed ignition lockout issue. If the wiring or connection at the burner gets rusted or damaged, the burner won’t get the electric power it needs to ignite the water heater. 

How To Fix: 

I recommend you visually inspect the burner wiring and its connection. If you observe any damage or sign of burn, you must replace the burner ground wire. In this case, you should visit the official website of Rheem to get the replacement part. This is how the ground wire for burner assembly looks like: 

burner ground wire

Keep in mind; all the electrical wiring must be performed by a certified electrician. If you are not electrically inclined, hire a professional electrician to replace the burner ground wire for you.  

02. Unplugged Connectors

Water heater connectors like igniter connector, temperature sensor connector, and others should be plugged for proper water heater operation. If these connectors remain unplugged, your water heater will perform intermittently like it will throw the trouble code ‘ignition failure’ on the display. 

How To Fix: 

Check all the connectors of your Rheem water heater. If any of them remain unplugged, plug them up. Don’t forget to inspect the connectors visually for damage. You must replace the connector or its wiring if it gets burnt. 

03. Faulty Flame Probe

One water heater issue that can throw a wrench into the work is a bad or defective flame probe. Every Rheem furnace has a flame sensor. If its probe gets dirty, you can’t ignite the unit anymore. Sometimes, the flame sensor itself goes bad, which is responsible for ignition failure. 

How To Fix: 

Replacing the flame sensor can be a straightforward solution to this issue. 

First off, turn off the power switch of your Rheem water heater. If you don’t find the switch, set the water heater’s circuit breaker to the off position. 

Secondly, slide the upper access panel of the water heater up and remove it from the unit. 

Thirdly, locate the flame sensor, which you can find at the front of your eyes. This picture shows you where the flame sensor is exactly on your water heater: 

This is where the flame sensor located

Now, use a flat head screwdriver to unthread the mounting screw that holds the flame sensor in place. Then, remove the old flame sensor. 

Take a look at the probe of the flame sensor. If it turns into black or yellow, you should use an emery cloth to remove the dirt deposits by rubbing the probe gently. Otherwise, you must replace the entire flame sensor. 

In this case, just get a new flame sensor and connect it with the wire. Then, carefully position the flame sensor on the burner bracket. Next, complete the installation by re-threading the mounting screw. 

04. Gas Shut-Off

Can you expect a water heater to run without gas? If the unit gets no gas supply for combustion, you can never ignite the unit. The unit will get no gas if you forget to turn on the manual gas shut-off valve. 

How To Fix: 

Check the manual gas shut-off valve and ensure it’s in the on position. If not, turn the gas manual shut-off valve clockwise to let the gas flow to the unit. Hope, it will help in deactivating the ignition lockout condition. 

05. Clogged or Defective Gas Valve

Failed ignition is a result from a clogged or faulty gas valve. When the gas valve gets restricted by fuel residue, no gas will flow to the combustion chamber. Consequently, you can’t ignite your Rheem furnace or water heater. 

A gas leak and complete water heater shut-down are some common signs that indicate there is a problem with the gas valve. 

How To Fix: 

You should replace the gas valve whether it gets blocked or defective. I highly suggest you call a professional to make the replacement. Alternatively, you can check out this article to replace the rheem water heater gas valve if you are mechanically inclined. 

06. Defective Control

A bad controller can also activate the ignition lockout condition. If the wiring of the water heater controller comes loose or gets damaged, the controller will not work anymore. And without a functional controller, you can’t turn on your Rheem water heater. 

How To Fix: 

The only option you have in your hand is to replace the controller if it gets defective. As it requires you to be involved in connecting and disconnecting electrical wires, I suggest you hand over this replacement workflow to a professional. 

Alternatively, you can watch this tutorial if you are electrically inclined and make the controller replacement by yourself: 

07. Dirty Burner

The burner chamber requires sufficient air or oxygen to ignite the flame. If the burner chamber gets dirty or clogged by dirt and debris, no air can flow into the burner chamber. And without air, it’s impossible to have a flame. In other words, you can’t light your water heater without enough oxygen. 

How To Fix: 

Cleaning the burner is a must to ignite the water heater. In this case, you should remove the burner assembly from the unit. So, pull out the burner assembly out of the unit and use a vacuum cleaner to clean the burner chamber. I recommend you watch the following video to learn how to clean the burner properly:

How To Get Rheem Water Heater Out of Ignition Lockout?

As I mentioned earlier, the ignition lockout condition results from a failure to establish burner ignition after 3 successive trials. If you want to get your water heater out of this condition, you should do the followings: 

  • Figure out the possible causes that may activate the ignition lockout condition and fix those problems. Above, I broke down every reason behind this condition and discussed what steps you should take to fix it. 
  • Once you investigate and solve those issues, it’s time to reset the lockout condition. So, keep pressing the red button on the display button momentarily to reset the ignition lockout condition. 
  • Finally, inspect your water heater for proper operation. 

How Do You Reignite a Rheem Water Heater?

Here’s how you can reignite a Rheem Water Heater: 

  • Turn the gas control knob to the Pilot position
  • Press and hold the gas control knob in.
  • While you press the gas control knob down, keep pressing the igniter button repeatedly until the pilot light comes on. 
  • Once the pilot light comes on, release the igniter button and the gas control knob.
  • Set the gas control knob to your desired temperature setting. 


Why does my Rheem water heater pilot light keep going out?

Rheem water heater pilot light will keep going out if the thermocouple wires get defective or thermocouple itself is at fault. Besides, dirty or bent thermocouple can cause the pilot light to go out repeatedly.

How do you reset the gas valve on a water heater?

To reset the gas valve on a water heater, ensure you set the pilot knob to the pilot position. Now, turn the gas control knob from the lowest setting to the very hot setting 7 times. It will reset the gas valve.

Alternatively, turn the gas control knob to the very hot setting for 10 seconds. Then, switch the dial to the hot setting for another 10 seconds. And finally, hold the gas control or temperature knob to the pilot position for 10 seconds.

What causes the reset button to trip on a gas water heater?

Excessive hot water, bad upper heating element, or bad thermostat are some culprits that cause the reset button to trip on a gas water heater.

How do I know if my gas valve is bad?

If there is a leak or the unit gets completely shut-down, understand the gas valve is at fault.

How do I know if my thermocouple is broken?

Get a multimeter and check the thermocouple wirings. If the resistance of its wiring gives a reading below 25 millivolts, understand the thermocouple gets broken and you need to replace it.


You can’t operate your Rheem water heater if it goes into the ignition lockout condition. But you don’t need to worry about it as I already mentioned those possible culprits responsible for this issue. Just do what troubleshooting steps I suggested and get the unit out of the ignition lockout condition. If the water heater still doesn’t function, don’t hesitate to call a professional. 

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