Charger shows E04 and refuses to charge, sometimes accompanied by a tripped RCD/RCBO in the distribution board.

Safety first: Ground fault conditions can be hazardous. Do not repeatedly reset breakers without identifying the cause. Isolate the charger from mains before inspection.

• 1. Inspect the charging cable and connector:
  • Check the entire length of the tethered cable for cuts, abrasions, or crushed sections.
  • Inspect the Type 2 plug for cracks, burn marks, or moisture.
• 2. Check for moisture ingress:
  • Open the charger housing following Heidelberg guidelines.
  • Look for condensation, water tracks, or corrosion on the main control board and around cable glands.
  • Dry the interior thoroughly with a dry cloth and allow to air dry; do not use high heat.
• 3. Inspect DC residual current sensor / IMD:
  • Locate the DC residual current sensor ring through which the power conductors pass.
  • Ensure it is firmly mounted and that no foreign objects or moisture are present.
• 4. Test with another vehicle (if safe):
  • If possible, test the charger with a different EV to rule out a vehicle‑side insulation fault.
• 5. If E04 persists:
  • The internal insulation monitoring device or DC residual current sensor may be defective.
  • Replacement of these components or the entire main control assembly should be performed by a qualified technician.