Bosch Mechanical Vibration of Contactor or Transformer

Bosch EV charger emits a loud humming or buzzing noise during operation.

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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

Loose mounting of internal contactor, Aging contactor coil, Loose enclosure mounting screws, Resonance from input transformer or choke

How to Fix / Troubleshooting

Safety first: Turn OFF power before tightening any screws or opening the unit.

  • Check mounting: Ensure the charger is firmly mounted to the wall or pedestal with all screws tight. A loose housing can amplify normal hum.
  • Listen for source: With the cover closed and power ON, carefully listen to identify if the noise is from the top, bottom, or side. Do not open the unit while energized.
  • Service inspection: A technician can open the unit, tighten the contactor mounting hardware, and inspect for coil buzzing due to wear. If the contactor is excessively noisy, replacement is recommended.
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Repair Difficulty

Medium 3/5

Required Part

Main Power Contactor / Input Filter Choke
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