Freezer displays E1 and interior temperature rises above setpoint, compressor does not start or starts briefly then stops.

Safety first: Unplug the Bomann freezer from the mains before removing any panels or touching wiring. Use insulated tools and avoid working on a wet floor.

Step-by-step checks:

• 1. Power-cycle the unit: Unplug for 5–10 minutes, then plug back in. If E1 clears temporarily and returns, continue with diagnostics.
• 2. Locate the cabinet NTC sensor: On most Bomann freezers, the cabinet temperature sensor is clipped behind the inner liner (often near the evaporator cover or side wall). Remove the interior plastic cover carefully to access the sensor.
• 3. Inspect wiring and connector: Check the sensor leads for cuts, pinches, or rodent damage. Ensure the connector at the sensor and at the main control board is fully seated and free of corrosion or moisture. Reseat connectors.
• 4. Test sensor resistance: With the unit unplugged, disconnect the NTC from the board and measure resistance with a multimeter. At around 20°C, many Bomann NTCs read roughly 5–10 kΩ (consult the service sheet if available). If the reading is open (infinite) or shorted (near 0 Ω), the sensor is faulty.
• 5. Check harness continuity: If the sensor tests good, test continuity from the sensor connector to the main board connector. Repair or replace damaged wiring.
• 6. Replace faulty parts: If the NTC or harness is defective, replace with a compatible Bomann cabinet temperature sensor assembly. If sensor and wiring are good but E1 persists, the main control board temperature input circuit may be defective and should be replaced.

When to call a technician: If you are not comfortable testing resistance or accessing the control board, or if the control board needs replacement, contact a qualified appliance technician.