E3
MUSTART
Overcurrent / Output Overload Protection
Display shows “E3” and charging stops or will not begin; may occur intermittently during storms or grid disturbances.
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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
EV drawing more current than charger setting, incorrect current setting on adjustable MUSTART model, internal current sensor fault on main control board, undersized branch circuit causing nuisance trips
How to Fix / Troubleshooting
Safety warning: Do not attempt to bypass overcurrent protection. This error prevents overheating and fire.
- Check current setting: On adjustable MUSTART chargers, verify the amp setting (e.g., 16 A, 24 A, 32 A, 40 A) is not higher than the circuit rating (80% of breaker size). For a 40 A breaker, set charger to 32 A or less.
- Reset charger: Unplug from the EV, turn off the breaker for 1–2 minutes, then restore power and plug in again.
- Try a lower current: If your model allows, reduce the current setting by one or two steps and see if E3 disappears.
- Check breaker and wiring (electrician): Have a licensed electrician verify that the branch circuit, breaker, and receptacle are correctly sized and connections are tight. If E3 persists at correct settings, the internal current sensor or main control board may be defective.
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Repair Difficulty
Hard
4/5
Required Part
Main Control Board (Current Sensing Circuit)
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