Display shows E4 and the wine cooler may stop cooling or run continuously.

Safety: Disconnect mains power before accessing the evaporator or electrical components.

Steps to address E4:

• Visual inspection: Remove interior rear panel to expose the evaporator and defrost components. Look for heavy ice buildup, burnt wiring, or damaged connectors.
• Check defrost sensor: Locate the defrost NTC (often clipped to the evaporator). Ensure it is firmly attached and not encased in thick ice. Test resistance with a multimeter; replace if open/shorted.
• Inspect defrost heater: The heater is usually a metal or glass-encased element at the base or around the evaporator. Check for visible breaks or burn marks. Test continuity; an open circuit indicates a failed heater.
• Defrost manually: If there is heavy ice, allow the unit to defrost fully with doors open. Do not use sharp tools to remove ice.
• Reconnect and test: After replacing any faulty sensor or heater, reassemble panels, restore power, and monitor for recurrence of E4.
• If E4 persists: The defrost relay or main control PCB may be defective. This typically requires a Neff service technician to diagnose and replace the board.