Charger displays E16; insulation resistance test fails and charging is blocked.

Safety first: Low insulation resistance can present a serious shock risk. Do not use the charger until resolved. Isolate power and lock out.

• 1. Visual inspection for moisture: Open the enclosure and look for water droplets, corrosion, or condensation on PCBs and terminals. Dry thoroughly and correct any sealing issues (replace gaskets, tighten glands).
• 2. Inspect Type 2 socket and cable: Check for cracks, water inside the socket, or damaged insulation. Replace any compromised components.
• 3. Megger test (technician only): With all power disconnected and following manufacturer limits, perform an insulation resistance test between live conductors and earth. Identify and replace any cable or component with low resistance.
• 4. Clean PCB surfaces: If contamination or tracking is visible on the power board, clean with appropriate PCB cleaner and a soft brush, then dry completely.
• 5. Replace IMD or main board: If external wiring and components are sound but E16 persists, the internal insulation monitoring device or its circuitry may be faulty. Replace the IMD module or main control/power board as applicable.