Porsche EV home charger displays E04; unit powers on but will not start charging when plugged into the vehicle.

Safety first: The main contactor switches high current. Do not attempt to service it while energized. Turn off the dedicated breaker and lock it out if possible.

• Listen for contactor operation: When starting a charge (with cover on), you should normally hear a distinct click. If E04 appears without a click, the contactor may be stuck or not driven.
• Technician inspection: A qualified technician should remove the wallbox cover and visually inspect the main contactor for discoloration, melted plastic, or signs of arcing.
• Check coil voltage: During a start attempt (under safe test conditions), the technician should measure the voltage at the contactor coil terminals. If the coil is not being energized, suspect the main control PCB or driver circuit.
• Replace contactor if welded: If the contactor contacts are welded or the mechanism is stiff, replace the complete contactor with a Porsche-specified part of the same rating. Do not attempt to file or repair contacts.
• Verify torque and wiring: Ensure all line and load conductors on the contactor are properly torqued to specification to prevent future overheating.