E4 appears on the display and the freezer interior light or fan may behave erratically.

Safety: Unplug the freezer before removing trims or accessing wiring. Avoid prying on plastic parts in cold conditions to prevent cracking.

Steps:

• 1. Check door closure: Ensure the door closes fully and evenly. Look for warped door, overfilled shelves, or items preventing full closure.
• 2. Inspect the door switch area: On many Neff freezers, the door switch is integrated into the cabinet frame or behind a small plastic cover near the top. Locate and visually inspect it for damage.
• 3. Test the switch (if accessible): With power disconnected, remove the switch cover and gently pull out the switch. Use a multimeter to check continuity while pressing and releasing the switch. A reed sensor may require moving a magnet near it.
• 4. Check the door magnet (if used): Some models use a magnet in the door to trigger a reed switch in the frame. Verify the magnet strip or insert is present and not loose.
• 5. Repair or replace: If the switch does not change state when operated, replace it with the correct Neff door switch or reed sensor. Reconnect wiring firmly and refit the cover.
• 6. Wiring and control: If the switch tests good, inspect the harness from the switch to the control module for breaks or pinched sections. If wiring is intact, the control board input may be faulty and should be checked by a technician.