E20
A.O. Smith
Upper Element / Thermostat Circuit Fault
A.O. Smith electric water heater shows E20 and does not heat properly
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Failed upper heating element, Open upper thermostat, Loose wiring at upper element, Tripped high-limit reset
How to Fix / Troubleshooting
Safety: Turn off the breaker and verify power is off with a meter before opening any panels.
- 1. Reset high limit: Remove the upper access panel and insulation. Press the red reset button on the ECO/high-limit switch until it clicks.
- 2. Inspect wiring: Check all screw terminals on the upper thermostat and element for tightness and signs of overheating. Tighten as needed.
- 3. Test element: With power off and wires removed from the element, measure resistance across the element terminals. An open reading indicates a failed element that must be replaced.
- 4. Replace thermostat: If the element tests good but there is no power leaving the upper thermostat when there should be, replace the upper thermostat assembly.
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Repair Difficulty
Medium
3/5
Required Part
Upper Heating Element
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