Err 10
AO Smith Internal Control Self-Test Failure

Display shows “Err 10” and the unit indicates an internal sensor or configuration error.

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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

Corrupted firmware, Internal sensor failure on PCB, Incorrect model configuration, Severe surge or lightning damage

How to Fix / Troubleshooting

Safety first: Disconnect power before removing the control panel.

Basic reset:

  • Unplug the unit for at least 5 minutes to allow capacitors to discharge.
  • Plug back in and observe whether the error clears on startup.
  • If the model supports it, perform a factory reset and re-enter all programming values.

Inspect the control board:

  • Remove the control cover and visually inspect the PCB for burn marks, cracked components, or moisture damage.
  • Ensure all harnesses are connected to the correct ports and fully seated.

If the error persists after reset and visual inspection, the electronic control board is likely defective and should be replaced with the correct AO Smith board for your model. Firmware on these boards is not field-repairable.

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Repair Difficulty

Hard 4/5

Required Part

Electronic Control Board
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