Freezer beeps and displays E1, temperature rises above setpoint and food begins to soften.

Safety first: Disconnect the freezer from mains power before removing panels or handling wiring. Use insulated tools and avoid working on live circuits.

Step-by-step checks:

• 1. Power reset: Unplug the freezer for 5–10 minutes, then reconnect. If E1 clears temporarily and returns, the sensor or wiring is likely faulty.
• 2. Locate the freezer NTC sensor: On most Neff freezers, the freezer temperature sensor is clipped behind a small plastic cover on the rear wall or side wall of the freezer compartment. Remove shelves and drawers as needed, then gently unclip the cover.
• 3. Inspect the sensor and wiring: Check for ice buildup around the sensor, damaged insulation, or pulled/chewed wires. If the sensor is encased in ice, fully defrost the freezer for 24 hours with the door open and towels in place, then test again.
• 4. Electrical test (for competent users): With the appliance unplugged, disconnect the sensor plug from the harness. Measure resistance across the sensor with a multimeter. A typical Neff NTC will read in the 5–30 kΩ range depending on temperature. An open circuit (OL) or 0 Ω indicates a failed sensor.
• 5. Replace the sensor if faulty: Order a Neff-compatible freezer NTC temperature sensor using the model number from the rating plate. Disconnect the old sensor, route the new sensor along the same path, and secure it with clips or tape as originally installed. Ensure the sensor tip is positioned in free air, not touching the evaporator directly.
• 6. Check the control module connection: If the sensor tests good, remove the top or rear service panel (depending on model) to access the main control module. Verify the sensor connector is fully seated and free of corrosion or burn marks.
• 7. When to call a technician: If the sensor and wiring are intact and E1 persists, the main control module input circuit may be defective. Replacement and programming of the control board is best handled by an authorized Neff service technician.