E10
United Chargers EV Communication / State Transition Error

E10 appears and the charger cannot communicate with the vehicle; charging does not start.

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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

Incorrect pilot voltage levels, Faulty control board analog front-end, Vehicle not responding to pilot changes, Poor ground reference between charger and vehicle

How to Fix / Troubleshooting

Safety first: De-energize the charger before internal work. Communication issues often require specialized test tools.

  • Test with another EV: Determine whether the issue is charger-specific or vehicle-specific.
  • Check grounding: Verify that the charger’s ground conductor is securely connected at both the charger and the service panel. Poor grounding can disrupt pilot communication.
  • Inspect connector pins: Ensure the J1772 pins are clean, straight, and fully seated. Lightly clean with contact cleaner if needed.
  • Firmware check: Update charger firmware if an update is available, as communication bugs are sometimes resolved in newer versions.

If E10 persists across multiple vehicles with proper grounding, the control board’s pilot interface circuitry may be defective and require replacement.

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Repair Difficulty

Hard 4/5

Required Part

Main Control Board
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