E03
Webasto
AC Supply Voltage Out of Range
Charger does not energize; display or app shows E03 overvoltage/undervoltage; charging stops intermittently during grid fluctuations.
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Incorrect supply wiring (single-phase vs three-phase), Loose line or neutral connection in terminal block, Utility voltage sag or surge, Faulty internal power supply board
How to Fix / Troubleshooting
Safety first: Only qualified persons should open the Webasto wallbox cover. Live terminals inside can cause lethal shock.
- Check other loads: Verify if lights or appliances in the home flicker or dim. If yes, contact your utility or electrician to check the service.
- Verify breaker rating: Ensure the Webasto charger is on a dedicated circuit with the correct breaker size as per the installation manual.
- Power cycle: Turn off the breaker for 2–3 minutes, then restore power and attempt charging again.
- Professional checks: Have an electrician measure line-to-line and line-to-neutral voltages at the charger input. Confirm they match the Webasto nameplate (e.g., 230 V single-phase or 400 V three-phase).
- If wiring or voltage is incorrect: Do not use the charger until the supply is corrected and all terminations are tightened to spec.
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Repair Difficulty
Professional Required
5/5
Required Part
Webasto Power Supply / Control Board
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