Cooktop shows F4 and all zones are disabled

Safety first: Turn off the appliance at the circuit breaker. Do not repeatedly reset if there is a burning smell or visible damage.

User-level reset:

• Leave the cooktop disconnected from power for at least 5 minutes to allow capacitors to discharge.
• Restore power and check if F4 clears. If the error returns immediately, further diagnosis is required.

Technician-level diagnosis:

• Remove the cooktop and access the main power board and user interface board.
• Inspect all wiring harness connectors between boards for secure fit and signs of overheating.
• Check for visible damage on the power board: burnt components, bulging capacitors, or cracked solder joints.
• Measure incoming supply voltage and verify correct phase and neutral connections according to Liebherr wiring diagram.
• If communication lines (often low-voltage bus) show no continuity or are shorted, repair or replace the harness.
• If harness is good and supply is correct, replace the main control/power board as a unit.