E09
Mercedes-Benz
Surge Protection / MOV Module Fault
Wallbox shows E09; charging does not start; often after a power outage or surge event.
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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
Failed metal-oxide varistor (MOV) surge protection module, Damage from lightning or grid surge, Burned surge protection PCB on Mercedes-Benz wallbox control assembly
How to Fix / Troubleshooting
Safety first: Isolate power at the breaker. Do not operate the wallbox if you suspect surge damage.
- Visual inspection: Open the housing and locate the surge protection module (often near the input terminals). Look for cracked components, burn marks, or a strong burnt smell.
- Check indicator (if present): Some surge modules have a visual indicator (green/red). If it shows red or ‘fault’, the module must be replaced.
- Do not bypass surge protection: Never remove or short the surge module to restore operation. This exposes the wallbox and vehicle to damage.
- Module replacement: Replacement of the surge protection module or combined input board should be done by an authorized Mercedes-Benz wallbox technician, who will also check for collateral damage to the control board.
- Consider additional protection: In surge-prone areas, consult an electrician about installing upstream surge protection at the main distribution board.
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Repair Difficulty
Hard
4/5
Required Part
Surge Protection Module (MOV Assembly)
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