Refrigerator compartment too warm while freezer seems normal; temperature alarm may sound and E1 appears on display.

Safety first: Unplug the Siemens refrigerator from the mains before removing covers or handling wiring. Do not work on live circuits.

Step-by-step checks:

• 1. Power reset: Disconnect power for 5–10 minutes, then reconnect. If E1 returns after a few minutes of operation, continue with diagnosis.
• 2. Locate the refrigerator NTC sensor: It is usually clipped to the rear wall or ceiling of the fresh-food compartment, often behind a small plastic cover or inside an air channel. Consult the Siemens service diagram (behind the kick plate or in the user manual) for exact location.
• 3. Inspect wiring and connector: Remove the sensor cover, gently pull out the sensor. Check for damaged insulation, pinched wires, or corrosion at the connector. Reseat the connector firmly.
• 4. Test the sensor with a multimeter: Set the meter to resistance (kΩ). At room temperature (~20 °C), most Siemens NTC sensors read between 4–15 kΩ (check your model’s spec). If the reading is open (OL), shorted (near 0 Ω), or far outside spec, the sensor is faulty.
• 5. Check continuity to the main PCB: If the sensor tests good, test continuity from the sensor connector to the main control board connector. Repair or replace any broken harness.
• 6. Replace parts as needed: If wiring and sensor are good but E1 persists, the main control board’s sensor input may be defective and require replacement.

When to call a technician: If you are not comfortable testing resistance or accessing the main control module, contact a qualified Siemens service technician.