E7
MUSTART
Ground Connection Fault / Protective Earth Missing
Display shows “E7” and the charger refuses to start; may occur when plugged into a miswired or ungrounded outlet.
Advertisements
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.
Advertisements
Possible Causes
Open ground in supply circuit, reversed hot/neutral on NEMA outlet, loose ground terminal in receptacle, internal ground connection fault at charger input
How to Fix / Troubleshooting
Safety warning: A missing or faulty ground is a serious shock hazard. Do not bypass the ground pin or use adapters that remove the ground.
- Stop using the outlet: If E7 appears, unplug the MUSTART charger and do not use that receptacle for EV charging until it is checked.
- Visual inspection: Look for obvious damage or looseness at the outlet. Do not remove the cover plate unless you are qualified.
- Outlet test (electrician or tester): Use a receptacle tester or have a licensed electrician verify correct wiring and a solid ground connection on the circuit.
- Try another properly wired outlet: If your charger model supports multiple plug types and you have another dedicated, correctly wired outlet, test there. If E7 persists on known-good circuits, the internal ground detection circuit may be faulty.
Advertisements
Repair Difficulty
Medium
3/5
Advertisements