Charger displays E04 and refuses to start; sometimes accompanied by a message about ‘overvoltage’ or ‘grid voltage too high’.

Safety first: Overvoltage can damage the charger and connected equipment. Do not continue to reset and retry if E04 persists.

Steps to try:

• Record the error: Note the time and conditions when E04 occurs (e.g. during low‑load periods or storms) for your electrician or utility.
• Check other appliances: If lights flicker or other devices behave oddly, there may be a supply issue. Contact your electricity provider.
• Power-cycle: Turn OFF the charger’s breaker for 1 minute, then ON again. If E04 clears and does not return, it may have been a transient spike.
• Have voltage measured: Ask a qualified electrician to measure line‑to‑neutral and line‑to‑line voltages at the charger terminals under load. Verify they are within Hager’s specified range (typically around 230 V ±10% single‑phase or 400 V ±10% three‑phase).
• If supply is normal: The internal voltage sensing circuit or main control board may be faulty and should be tested and replaced by a technician.