AO Smith Water Heater Error Code 002: Water Temperature Exceeded High Limit (Meaning, Causes, Fixes)

What the code means

In A. O. Smith's Residential Electronic Thermostat Electric Water Heater Use and Care Guide (the Wi-Fi, Energy Smart display model sold at Lowe's), diagnostic code 002 with a flashing alert icon, flashing red LED and beeper is listed as Water temperature exceeded high limit. The same guide explains that the Energy Cut Off (ECO) shuts off power to the elements if the tank water gets too hot, so you'll have no hot water until it's reset. A. O. Smith also says a tripped ECO usually means the tank overheated because of a problem with one of the elements or thermostats, and that the power shouldn't stay on until the cause of the overheating has been found and repaired. Older A. O. Smith electric heaters with the Energy Smart Module (ESM) show the same fault as E02, and their Electronic Thermostat LED blinks 2 red flashes. Don't confuse 002 with 001, which is a dry-fire code for power on with the tank not completely full of water.

Likely causes

• A heating element shorted to the tank (a grounded element), which keeps heating even when the thermostat isn't calling for heat. A. O. Smith's first repair step if 002 returns is to test for a grounded element
• A failed electronic thermostat. The guide says to replace the thermostat if both elements test good
• Water temperature set very high. The guide's no-code Water Too Hot entry lists a high setting or a grounded element as the causes
• A one-time overheat that tripped the ECO. If it resets with a click and doesn't come back, no part may need replacing

Safe DIY checks

1. If the water at your taps is very hot, warn everyone in the house and don't use it for bathing until it's back to normal.
2. Turn off the water heater's breaker (or remove its fuses). A. O. Smith's guide has you confirm the power is off at the junction box on top of the heater with a non-contact circuit tester before working inside.
3. Open the access panel over the electronic thermostat and press the red ECO reset button (A. O. Smith's guide shows it in Figure 26). The guide says that if you hear a click, the ECO was tripped.
4. Put the insulation and access panels back, secure all covers, and turn the breaker back on. Check that 002 has cleared and the heater starts heating.
5. Check your temperature setting on the display and lower it if it's set high. A. O. Smith recommends 120°F to reduce scald risk.
6. If 002 comes back, stop resetting it and leave the power off. A. O. Smith's guide says a repeat means a qualified technician should test the elements, and its instructions are meant for a qualified person. You can also call the Technical Assistance Hotline on your warranty sheet.

Parts that commonly fix it

Always match the part number to your exact model.

Related codes

• 031 AO Smith Electric Water Heater 031
• 084 AO Smith Heat Pump Water Heater 084
• E09 Bosch Dishwasher E09
• E15 Bosch Dishwasher E15
• E22 Bosch Dishwasher E22

All AO Smith codes →

Sources

1. A. O. Smith Residential Electronic Thermostat Electric Water Heater Installation Instructions and Use & Care Guide (aosmithatlowes.com): diagnostic code 002 (Water temperature exceeded high limit) and its corrective actions, 001 dry-fire, Water Too Hot, and the Check/Reset Energy Cut Off (ECO) steps with Figure 26
2. A. O. Smith Residential Electric water heater guide with Energy Smart Module (aosmithatlowes.com): E02 with alert icon and 2 red flashes on the Electronic Thermostat, Water temperature exceeded high limit, reset button steps