F4
Hoover H-Free Main Control PCB Fault

F4 displayed, unit will not respond to trigger, LEDs may light briefly

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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 microcontroller on main PCB, Liquid ingress onto electronics, Shorted internal component after surge

How to Fix / Troubleshooting

Safety: Remove the battery immediately if you suspect liquid has entered the unit. Do not attempt to use or charge a wet appliance.

  • Inspect for moisture: Check around the dust bin, filter area, and vents for signs of water or sticky residue. If present, the internal PCB may be damaged.
  • Power reset: Remove the battery for 5 minutes, then refit and test. This may clear transient faults but will not fix hardware damage.
  • Check for visible damage: Look for burn marks or melted plastic around vents or the battery connector.
  • Professional repair: The main PCB is inside the handheld body and requires full disassembly. Contact an authorised Hoover service centre to replace the main control PCB.
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Repair Difficulty

Professional Required 5/5

Required Part

Hoover H-Free Main Control PCB
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