Charger displays E03 and refuses to start; vehicle may show a charging fault message.

Critical safety warning: An earth fault can be dangerous. Do not bypass or defeat ground protection. If you are not qualified to test mains wiring, contact an electrician.

• Disconnect everything: Unplug the J+ Booster from the mains and vehicle.
• Check for adapters: Ensure you are not using ungrounded travel adapters or two-pin extension cords. The J+ Booster must be connected to a properly grounded outlet.
• Inspect the supply plug: Look for a broken or bent earth pin. If the earth pin is damaged, stop using the charger.
• Test the outlet ground: Use a socket tester or have an electrician verify that the outlet has a correct earth connection.
• Check input cable strain relief: If the J+ Booster is hardwired or has a detachable input cable, ensure the cable is not pulled out of the housing and that the strain relief is intact.
• If E03 remains on a known-good grounded outlet: The internal ground monitoring circuit on the main control board may be defective and requires professional replacement.