Freezer display shows F1 and temperature rises above setpoint, compressor not running or cycling very briefly

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

• Power reset: Disconnect power for 5–10 minutes, then reconnect. If F1 clears temporarily and returns, the sensor circuit is likely faulty.
• Locate the freezer NTC: On most Bauknecht upright freezers, the freezer temperature sensor is clipped behind the inner liner, often near the evaporator cover or rear wall. Remove the internal shelves and the rear plastic panel (if accessible) to expose the sensor.
• Inspect wiring and connector: Check the NTC leads for cuts, pinches, or rodent damage. Ensure the connector at the sensor and at the main control board (usually in the top or rear control housing) is fully seated and not corroded.
• Test the sensor: With a multimeter set to resistance, measure the NTC at room temperature. Typical Bauknecht NTCs are around 4.7–10 kΩ at 25°C. If the reading is open (infinite) or shorted (near 0 Ω), the sensor is defective.
• Replace if faulty: If the NTC is out of spec, replace it with a compatible Bauknecht freezer temperature sensor. Route the new sensor wiring along the original path and secure it away from moving parts and sharp edges.
• Check the control board: If the sensor tests good but F1 persists, inspect the main PCB for burnt components or damaged tracks at the NTC input. At this point, replacement of the main control board is usually required and is best done by a qualified technician.