E03
United Chargers Contactor / Relay Welded or Stuck

Display shows E03 and charging stops or will 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

Welded main power contactor, Contactor coil failure, Control board output failure to contactor, Overheated or carbonized contactor terminals

How to Fix / Troubleshooting

Safety first: Turn off the upstream breaker and verify absence of voltage with a meter before opening the charger. A welded contactor can leave live voltage at the output even when the charger appears off.

  • Power reset: Turn breaker OFF for 5 minutes, then ON. If E03 returns immediately, suspect a hardware fault.
  • Listen for contactor operation: When starting a charge, you should hear a distinct click from inside the charger. No click or a continuous hum suggests a contactor or control issue.
  • Internal inspection (qualified only): Remove the cover and locate the main power contactor. Check for discoloration, melted plastic, or burnt smell. Verify coil and line/load terminals are tight.
  • Continuity test: With power OFF and cables disconnected from the vehicle side, measure continuity across the contactor output. If continuity is present when the charger is idle (no charge command), the contactor is welded closed and must be replaced.

Do not attempt to free a welded contactor by tapping or prying; replace it with the correct United Chargers-specified contactor model.

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Repair Difficulty

Professional Required 5/5

Required Part

Main Power Contactor
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