Display shows E04 shortly after starting a charge; charging stops and vehicle reports an earth leakage or RCD trip.

Safety: Treat all ground fault indications as serious. Do not repeatedly reset and continue charging without investigation.

• Unplug and dry: Disconnect from mains and vehicle. If the charger or connector has been exposed to rain or washing, allow it to dry in a warm, ventilated area for at least 24 hours.
• Inspect cable and connector: Look for cuts, abrasions, or crushed sections of the output cable. Check the connector for moisture, corrosion, or burn marks.
• Try another vehicle (if possible): If E04 only occurs with one vehicle, the fault may be in that vehicle's onboard charger.
• Test on a different outlet: Use a properly grounded, dry outlet to rule out supply-side leakage.
• Do not open the unit: The internal RCD sensor and electronics are not user-serviceable. If E04 persists with different vehicles and outlets, the J+ Booster should be inspected by a qualified technician.