F9
Liebherr Communication Fault Between User Interface and Main Control Board

F9 displayed; audible alarm may sound; temperature may drift and not match setpoint.

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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 or damaged communication harness, Faulty user interface PCB, Defective main control PCB

How to Fix / Troubleshooting

Safety first: Disconnect mains power before removing any panels or boards.

Steps:

  • 1. Access control area: Remove the top/front control panel and rear electronics cover as needed to expose both the user interface and main PCB.
  • 2. Inspect harness: Locate the multi-core cable or ribbon connecting the two boards. Check for pinched, cut, or abraded sections.
  • 3. Reseat connectors: Unplug and firmly reconnect both ends of the harness, ensuring correct orientation and full insertion.
  • 4. Look for corrosion: Any green/white corrosion on pins indicates moisture damage; clean gently with contact cleaner and a soft brush, then dry thoroughly.
  • 5. Power up and test: Restore power and see if F9 clears. Test all buttons and display functions.

Escalation: If the error persists, either the user interface or main PCB is defective. Component-level diagnosis and replacement should be performed by a qualified technician.

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Repair Difficulty

Hard 4/5

Required Part

Control Harness / User Interface PCB
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