Freezer displays E1 and temperature rises above set point; compressor may not run or runs briefly then stops.

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

Step-by-step checks:

• Power cycle: Disconnect power for 5 minutes, then reconnect. If E1 returns within a few minutes, continue with diagnosis.
• Locate the cabinet sensor: On most Blomberg freezers, the cabinet NTC is clipped behind an interior liner panel or in a small plastic housing on the rear wall. Remove the inner cover carefully without damaging the foam insulation.
• Inspect the sensor and wiring: Check for broken insulation, pinched wires, or corrosion at the connector where the sensor plugs into the harness. Reseat the connector firmly.
• Resistance test: With the unit unplugged, disconnect the NTC from the harness and measure resistance with a multimeter. At room temperature (20–25°C), most Blomberg NTCs read roughly 4–15 kΩ. An open circuit (OL) or near 0 Ω indicates a failed sensor.
• Check harness to PCB: Follow the harness to the main control board (usually in a rear lower compartment). Ensure the plug is fully seated and not heat-damaged or oxidized.
• If sensor is out of spec: Replace the cabinet NTC sensor with a Blomberg-compatible part. Route the new sensor along the original path and secure it away from moving parts or sharp edges.
• If sensor and wiring test good: The temperature input circuit on the main PCB may be faulty. Replacement of the main control board is typically required and is best done by a qualified technician.

Test: Reassemble panels, restore power, and monitor for several hours. Confirm that E1 does not reappear and that the freezer reaches and maintains the set temperature.