Porsche EV home charger displays E20; internal insulation monitoring detects a fault and charging is blocked.

Safety first: Isolation faults can lead to electric shock. Turn off power at the breaker and do not use the charger until tested.

• Visual inspection: Check the external cable and plug for cuts, abrasions, or signs of water ingress. Replace the cable assembly if any damage is found.
• Drying period: If the wallbox has been exposed to heavy rain or washing, allow it to dry thoroughly with power off for at least 24 hours.
• Technician insulation test: A qualified electrician should perform insulation resistance tests on the output circuits and internal wiring using a megohmmeter, following Porsche’s limits.
• Clean internal components: If contamination is found on busbars or terminals, clean with appropriate electrical cleaning agents and replace any carbon-tracked components.
• Replace monitoring circuit: If insulation is good but E20 persists, the insulation monitoring circuit on the main control PCB may be defective and require board replacement.