A. O. Smith E02 Code on an Electric Water Heater

The Short Answer: E02 appears on A. O. Smith-built electric tank heaters with a digital control, and it is commonly reported as a high-temperature (high-limit) shutdown. We could not confirm that meaning in A. O. Smith’s published manuals, so check the code label inside the heater’s access door or the manual for your model. Until you do, treat the water as possibly too hot and do not keep resetting the heater.

Confirm the code for your heater

A. O. Smith, State, American and several store brands built by A. O. Smith share electronic controls, but code lists differ between product lines and generations. For example, A. O. Smith’s newer smart heat pump models use three-digit codes such as 001 for dry fire and 021 for an upper element fault, listed in use and care guide 100361198 (opens in a new tab). That list does not include E02.

To get the right meaning:

1. Note the full model and serial number from the rating plate.
2. Look for a code chart on a label near the display or inside the upper access panel (do not remove panels to look; many charts are on the outside).
3. Check the use and care guide in the pocket on the heater, or download it using A. O. Smith’s model and manual lookup (opens in a new tab).
4. A. O. Smith’s manuals list a technical assistance line, 1-800-527-1953, for codes not in the manual.

If you have a gas heater, a heat pump (hybrid) heater, or a tankless heater, E02 is not this code; see A. O. Smith hybrid problems or the error code hub.

If E02 is a high-limit shutdown

Electric tank heaters have an energy cutoff (ECO), a safety that disconnects the elements if the water gets far hotter than the setpoint. On models with a digital control, the control reports that event as a code. The usual reasons the water overheats:

• A thermostat or control that keeps an element on after the setpoint is reached.
• An element that has shorted to the tank, so it keeps heating regardless of the control.
• Rarely, a very high setpoint combined with heavy, repeated short draws.

Each of these needs a technician once it has happened more than once. A single trip after a power disturbance can be a one-off.

What you can do safely

• Check the water temperature at a tap, carefully. Very hot water, or steam and sputtering from the tap, means the overheat was real.
• Look at the relief valve discharge pipe. If it is releasing water or steam, turn off the heater’s breaker and leave it off.
• Check the setpoint on the display. If it is set much higher than about 120°F, note it for the technician.
• Reset once. Follow the reset steps in the manual for your model. Many digital controls clear a code when power is turned off at the breaker and back on. If E02 returns, leave the breaker off.

Do not open the access panels, press internal reset buttons, or test elements yourself. Those parts are on a 240-volt circuit.

What the technician will check

The technician confirms the code against the model’s service documents, then checks whether the control and thermostat switch off at setpoint and tests each element for a short to the tank. A failed element is a routine repair. A control or thermostat that stuck on is replaced along with any element it damaged, and the technician will check wiring for heat damage. A tank that is also leaking means replacement. For background on this kind of failure, see what causes a water heater thermostat to burn up and why you keep having to reset a water heater.

Frequently Asked Questions

Q: Is E02 dangerous? A: If it is an overheat code, the safety did its job and stopped the heating. The risk is the hot water already in the tank and repeated resets that let a faulty control overheat it again.

Q: Can I keep using hot water while I wait for service? A: With the breaker off, the tank cools over time and you can use what is left, carefully. Do not restore power to get more hot water if the code keeps coming back.