F4
Toshiba Motor Speed Control / Tachometer Feedback Fault

Vacuum shows F4 and cannot maintain suction; motor speed surges up and down

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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

Faulty motor tachometer sensor, Loose motor connector, Damaged motor driver circuit on main PCB, Worn motor brushes (on brushed designs) or failing BLDC motor

How to Fix / Troubleshooting

Safety first: Remove the battery before opening any covers. Do not run the motor with covers removed.

  • Step 1 – Check for airflow restrictions: Ensure filters and airways are clean. Sometimes the control system misinterprets heavy load as a speed fault.
  • Step 2 – Soft reset: Remove the battery for 5 minutes, then reinstall and test. If F4 persists, internal components are likely at fault.

When to call a technician: Diagnosing tachometer and driver faults requires access to the motor and PCB and specialized tools. The typical repair is replacement of the motor assembly or entire main body module.

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Repair Difficulty

Professional Required 5/5

Required Part

Main Suction Motor Assembly
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