F4
Miele Main Control PCB Fault

Vacuum does not respond to trigger or power button, F4 displayed or LED flashes rapidly when battery inserted

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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

Defective main control PCB in handle or power unit, Internal short in wiring harness, Firmware corruption, Liquid ingress on electronics

How to Fix / Troubleshooting

Safety first: Remove the battery pack and disconnect the charger. Do not continue to operate a unit that has been exposed to liquids.

  • 1. Power reset: Remove the battery for at least 5 minutes. Press and hold the power button for 10 seconds (with battery removed) to discharge residual power. Reinsert the battery and test.
  • 2. Inspect for liquid damage: Check around the handle, display, and battery compartment for signs of moisture, corrosion, or sticky residue. If liquid ingress is suspected, do not attempt to use the vacuum. Internal components must be inspected and cleaned by a professional.
  • 3. Check wiring harness (visual only): If accessible without disassembly (e.g. at the battery connector), look for pinched or damaged wires. Do not pull on wires.
  • 4. Firmware / PCB issue: If F4 persists after reset and there is no visible damage, the main control PCB is likely defective. This requires replacement of the handle or motor unit assembly by a Miele service center.
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Repair Difficulty

Professional Required 5/5

Required Part

Main Control PCB
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