Kia EV charger displays E04 and charging stops or never begins when the vehicle is connected.

Safety first: Overvoltage can damage both the charger and the vehicle. Do not repeatedly reset and force charging if E04 persists.

• 1. Measure supply voltage: Have a qualified electrician measure line-to-line and line-to-neutral voltage at the charger input while under light load. Compare with the charger’s rating label (e.g., 230 V single-phase or 400 V three-phase).
• 2. Check for loose neutral: In systems using neutral, a loose or broken neutral can cause one leg to rise above nominal voltage. The electrician should tighten all terminations and correct any wiring errors.
• 3. Verify breaker and cable sizing: Ensure the charger is connected to the correct circuit breaker size and cable gauge as specified in the Kia installation manual. Oversized voltage from miswired phases can trigger E04.
• 4. Monitor grid fluctuations: If the supply is within spec most of the time but spikes occasionally, consider installing a whole-house surge protector or voltage stabilizer as recommended by your electrician.
• 5. Internal board check: If measured voltage is normal but E04 persists, the input voltage sensing circuit on the main control board may be faulty. In that case, the main control board should be replaced with a Kia-approved part.

Do not attempt to modify the charger’s internal voltage sensing or bypass safety features. Persistent E04 requires professional diagnosis.