AO Smith Water Heater Error Code 022 (22): Lower Element Circuit Failure (Meaning, Causes, Fixes)

What the code means

In A. O. Smith's Residential Electronic Thermostat Electric Water Heater Use and Care Guide, diagnostic code 022 with a flashing alert icon, flashing red LED and beeper is listed as Lower element circuit failure, with the notice that the upper element is still operable. The Residential Hybrid Electric Heat Pump Water Heater Service Handbook (HPTS, HPTA and HPTV models and their HPS10, HPA10 and HPV10 retail versions) lists the same code and the same steps. When the control decides the lower element (or, on the electric model, the lower thermistor) has failed, it cancels the lower element's call for heat and goes into limp mode: on the electric model the upper element keeps heating the water, and on the hybrid the upper element covers the lower element's call for heat (A. O. Smith calls this Limp Mode 2). The heater stays in limp mode until the failure is fixed, which is why you'll usually notice hot water running out sooner. Its twin code is 021, upper element circuit failure, where the lower element keeps working instead.

Likely causes

• A burned-out lower heating element. A. O. Smith's guide notes that the lower element does most of the work, so it usually wears out before the upper one
• A grounded or shorted lower element, which A. O. Smith's element test checks for by measuring from each terminal to the element flange or tank shell
• Damaged, burned or loose wires at the lower element, the thermostat or the control assembly board, which A. O. Smith's 022 steps say to inspect
• On the electric model, a failed lower thermistor (temperature sensor), which A. O. Smith's limp mode description lists alongside a failed lower element

Safe DIY checks

1. Turn off the water heater's breaker and confirm the power is off with a non-contact circuit tester. A. O. Smith warns that working near an energized circuit can cause severe injury or death from electrical shock.
2. Remove the lower access panel and insulation so you can reach the lower element's terminals. Look for burned, melted or loose wires there and at the thermostat and control board connections, as A. O. Smith's 022 steps say.
3. With the power off, disconnect one wire from the lower element and measure across the two element terminals with a multimeter. A. O. Smith's code chart says the element circuit should read 5 to 25 ohms; an open reading or one far outside that range means the element needs replacing.
4. Also check for a grounded element: put one probe on an element terminal and the other on the element flange or tank shell. A. O. Smith's handbook says any continuity means the element is grounded and should be replaced.
5. To replace the element, A. O. Smith's procedure is to turn off the power and the cold water supply, run a hot faucet until the water is cool, drain the tank with a garden hose, remove the power wires and unscrew the old element with an element wrench. Fit a new element that matches the voltage and wattage on the heater's data plate, with a new rubber gasket lightly lubricated with a drop of dish soap.
6. Refill the tank completely and open a hot water faucet until all air is out before turning the power back on. A. O. Smith says the tank must be completely full of water first, since powering an empty tank can burn out the upper element (dry firing).
7. Turn the breaker back on. If the wiring and element check out and 022 still shows, A. O. Smith's next step is to contact a qualified person. On the hybrid models, the service handbook says you can clear a code from the display temporarily by pressing the Up and Down temperature buttons together until it shows CLR, but it will come back until the fault is fixed.

Parts that commonly fix it

Always match the part number to your exact model.

Related codes

• 002 AO Smith Electric Water Heater 002
• 031 AO Smith Electric Water Heater 031
• 084 AO Smith Heat Pump Water Heater 084
• 7 flashes AO Smith Gas Water Heater 7 flashes
• E07 Bosch Dishwasher E07

All AO Smith codes →

Sources

1. A. O. Smith Residential Electronic Thermostat Electric Water Heater Installation Instructions and Use & Care Guide (aosmithatlowes.com): diagnostic codes 021 and 022, Limp Mode, lower heating element not working, Replacing the Heating Element, dry firing notice
2. A. O. Smith Residential Hybrid Electric Heat Pump Water Heater Service Handbook (assets.hotwater.com): diagnostic code 022, Limp Mode 1 to 3, clearing error codes (CLR), grounded element test, Replacing Heating Element
3. A. O. Smith Residential Electronic Thermostat Electric Water Heater Use & Care Guide 100362786 (Consolidated Supply copy): diagnostic code 022 (Lower element circuit failure)