Display shows E2 and the freezer runs continuously or not at all, with unstable internal temperature.

Safety warning: Always unplug the freezer before removing internal panels or working near the evaporator. Edges can be sharp; wear cut-resistant gloves.

Steps to diagnose and correct:

• 1. Defrost access: Remove drawers and the rear inner panel of the freezer compartment (usually held by screws or clips) to expose the evaporator. If heavily iced, allow to defrost fully before proceeding.
• 2. Locate the evaporator sensor: On Neff freezers, the evaporator NTC is typically clipped to the evaporator tubing or embedded in a small plastic housing attached to the coil.
• 3. Visual inspection: Check that the sensor is firmly clipped in place and not hanging loose. Look for crushed, cut, or corroded wires, especially where they pass through the cabinet.
• 4. Test the sensor: With the appliance unplugged, disconnect the sensor from its connector and measure resistance with a multimeter. Compare to the freezer sensor if known-good, or to Neff service data if available. An open or shorted reading indicates failure.
• 5. Replace if necessary: Order the correct Neff evaporator NTC sensor. Unclip the old sensor, route the new one along the same path, and secure it to the evaporator coil as originally installed to ensure accurate defrost control.
• 6. Check harness to control board: Trace the sensor wires to the main control module. Ensure the connector is fully seated and not heat-damaged. Repair any damaged wiring with appropriate connectors and insulation.
• 7. Control board consideration: If a new sensor does not clear E2, the main control module may be misreading the sensor. At this point, professional diagnosis and possible board replacement are recommended.