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

Safety first: Unplug the Siemens freezer from the mains before removing any panels. Do not work on live circuits.

Step-by-step checks:

• 1. Power reset: Disconnect power for 5–10 minutes, then reconnect. If E1 clears briefly and returns, continue with hardware checks.
• 2. Locate the freezer NTC sensor: Inside the freezer compartment, look for a small plastic cover on the rear or side wall (often near the evaporator cover). Remove the cover carefully.
• 3. Inspect the sensor and wiring: Check the NTC sensor body for cracks, ice intrusion, or discoloration. Follow the two-core cable to ensure it is not pinched, cut, or chewed.
• 4. Check connections at the control board: Remove the top or rear control housing (depending on model). Find the connector labeled for the freezer NTC. Reseat the plug several times to clean contacts.
• 5. Test the sensor (for advanced DIYers): With the appliance unplugged, disconnect the sensor and measure resistance with a multimeter. At around -18°C, Siemens NTC sensors typically read in the tens of kΩ range (consult service data if available). An open circuit (infinite) or 0 Ω indicates a failed sensor.
• 6. Replace if faulty: If resistance is out of range or intermittent when you gently flex the cable, replace the freezer NTC sensor with a Siemens-compatible part. Route the new cable along the original path and secure it away from moving parts and sharp edges.
• 7. Reassemble and test: Refit covers, restore power, and monitor the display. The E1 code should clear after a short run period if the fault is resolved.

When to call a technician: If the sensor tests correctly but E1 persists, the main control board may be misreading the signal and should be diagnosed or replaced by a professional.