AO Smith Water Heater Error Code E2? Find Solutions Here

AO Smith Water Heater Error Code E2

AO Smith is a leading provider of water heater and water treatment solutions. Unfortunately, you may encounter the AO Smith water heater error code E2 when using your water heater. If you’re wondering what this means and how to fix it, this is the article for you!

What Does E2 Error Mean?

You may start panicking if you see an E2 error code on your AO Smith water heater. The E2 error code means that your water temperature exceeded its high limit.

How Do I Fix Error Code E2?

First, you should begin by turning off the electrical power at the breaker. You don’t want to work on your water heater while the power is still on. Next, you’ll want to press the reset button on your water heater near the top of the electronic thermostat.

Now that you’ve hit the reset button, you can turn the electrical power back on at the breaker. This should be enough to resolve the issue. If not, or if the error returns, you will have to call a service technician for additional assistance.

How do I fix error code E2

AO Smith Signature Premier Water Heater Error Codes E02

One of the good things about AO Smith water heaters is that they are all self-diagnostic. This means that if there is a problem with your water heater, the heater will tell you itself, typically by displaying an ESM (or error code) with a flashing icon.

If you aren’t sure whether your AO Smith water heater is experiencing a problem, check whether the remote (if one has been installed) or the electric board is displaying a three-digit error code. If not, all is well. If so, and if that error code is e02, the above steps should help.

Sometimes, however, you may see a different error code displayed on your electric board. If this is the case for you, continue reading, and see our tips below for dealing with a variety of other possible AO Smith water heater fault codes.

AO Smith Water Heater Error Code E01

If your water heater shows E01 rather than E02 as the error code, it means that your water heater is experiencing a different problem. Error code E01 indicates a dry fire, which means the tank is not full of water and the electrical power is still on.

So, how do you resolve this issue? The AO Smith diagnostic code chart recommends the following three steps.

  1. Begin by turning off electrical power at the breaker, and then add water.
  2. Next, turn the electrical power back on.
  3. Finally, you should read page 4 of the use and care guide for important safety tips when working with your water heater.
AO Smith Water Heater Error Code E01

AO Smith Water Heater Error Code E03

There are many other possible error codes you might see displayed on your AO Smith water heater, and one of those is error code e03.

Error code e03 means that your water heater is experiencing an upper thermistor sensor failure. The upper thermistor sensor is part of the electronic thermostat (ET).

If this is the error code your water heater is displaying, you can follow these corrective action steps to resolve the issue.

  1. First, turn off the electrical power at the breaker.
  2. Next, you will need to replace the electronic thermostat (ET) fully.
  3. Once you’ve completed this step, you can turn the power back on at the breaker, and the error code should disappear.

AO Smith Water Heater Error Code 6-1

If you see error code 6-1 displayed on your water heater, it may be the case that you have ignition or flame failure. The ignitors in your water heater wear down over time and need to be replaced. That said, there are several different possible causes for this error code.

Typically, this is an error code that will likely require professional assistance. However, if you’d like to try to figure out the cause and solve the problem on your own, you can refer to the following steps.

AO Smith water heater error code 6-1

1. Low Gas Supply

It might be that your gas supply is too low or turned off. Ensure your gas supply is set up as it should for your respective model.

2. Low Voltage

Your voltage may be low and will need to be corrected if this is the case.

3. Flame Sensor

Your flame sensor should be in good contact with the burner flame. If not, this may be the cause of error code 6-1. Your flame sensor should also be clean. You can clean it with steel wool if it is dirty.

4. Hot Surface Ignitor

You may need to verify that the hot surface ignitor is well positioned to provide consistent ignition. For example, there could be cracks in the ignitor assembly ceramic insulators. If so, the damaged ignitor assembly will have to be replaced.

Ensure that the ignitor’s resistance is within the proper range while at room temperature.

6. Vent Pipe

Ensure that your vent pipe is the correct size according to the installation manual. It may be 2 inches, 3 inches, or 4 inches. Using a pipe of the wrong size can generate air turbulence in the combustion chamber, which can generate error code 6-1.

How Do You Reset the Error Code on the AO Smith Water Heater?

You can reset the AO Smith water heater error code E2 (or any other AO Smith water heater troubleshooting codes) by turning off the electrical supply to your water heater at the electrical breaker in your home.

Remove the panel covering from the side of your AO Smith unit (you’ll need a screwdriver). Once you’ve done this, you can find the AO Smith tankless water heater reset button inside the panel, usually underneath some insulation.

After you hit the reset button, you should hear a clicking sound to indicate you successfully reset the water heater. You can screw the panel back and turn the electrical supply to the water heater back on.

Congratulations! You’ve successfully reset the E2 code on your heater (or any other error code).


Hopefully, you feel more confident performing AO Smith tankless water heater troubleshooting. Seeing error codes displayed on your water heater can be scary. You may not know exactly what they mean, and even if you do, you may not know how to resolve them.

Our tips above should help you identify the problems and begin to solve them on your own if you come across the AO Smith water heater error code E2.

The most important piece of advice to remember is to be cautious. If you feel that you cannot adequately resolve an issue on your own, it may be best to call a service professional or technician and allow them to assist you.


What does E2 mean in electrical?

An E2 code is an indicator that there’s an electrical problem inside your unit or device.

Why is my AO Smith water heater not working?

Several reasons your heater may not be working include error codes or electrical or valve issues.

Why can’t I reset my water heater?

If you’re unable to reset your water heater, you may have a faulty thermostat or other electrical issues.

How long is the AO Smith water heater warranty?

Most AO Smith water heaters come with a warranty of between 6 and 12 years. Refer to the paperwork that came with your unit, or call AO Smith customer service for more information.

How do I fix the E2 error on my Trane thermostat?

You can start by checking the return temperature sensor, as this code may indicate a problem. If there’s an issue, you’ll need to replace the thermostat.

How do you reset the error code on an AO Smith water heater?

First, turn off the electrical supply to your heater. Then, remove the panel from the side and find the reset button.