F9
Xiaomi
Internal Self-Test / MCU Fault
Display shows F9, vacuum cannot start due to internal self-test failure
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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
Corrupted firmware, Failed microcontroller on main PCB, Severe sensor mismatch, Liquid damage on control board
How to Fix / Troubleshooting
Safety first: Remove the battery and do not attempt to operate a liquid-damaged unit.
- Power cycle: Remove the battery for at least 5 minutes, then reinstall and try again. This can clear transient faults.
- Check for liquid or corrosion: Inspect the exterior for signs of liquid ingress. If the vacuum was exposed to water, do not power it on. Allow it to dry for at least 48 hours in a warm, dry place.
- Firmware update (if accessible): If the vacuum can still connect to the Xiaomi Home app, check for and apply any firmware updates.
- If F9 remains: The main control PCB is likely defective. Board replacement is the recommended repair; component-level repair is not practical for most users.
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Repair Difficulty
Professional Required
5/5
Required Part
Main Control PCB
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