Freezer display shows E1 and interior temperature is too high or fluctuates; compressor may run continuously.

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

Step-by-step checks:

• 1. Power reset: Disconnect power for 5–10 minutes, then reconnect. If E1 clears temporarily and returns, the sensor or wiring is likely faulty.
• 2. Locate the cabinet NTC: On most Gram freezers, the cabinet temperature sensor is behind an interior plastic cover on the rear or side wall, often near the evaporator cover or light housing.
• 3. Inspect wiring and connector: Remove the interior cover carefully. Check the NTC sensor leads for cuts, pinches, or signs of moisture ingress. Ensure the connector to the wiring harness is fully seated and not corroded.
• 4. Test the sensor: With the freezer unplugged, disconnect the NTC from the harness and measure its resistance with a multimeter. At around 25°C, most Gram NTCs read roughly 5–10 kΩ (check service data if available). If the reading is open (∞), shorted (~0 Ω), or wildly off, the sensor is defective.
• 5. Check continuity to the PCB: If the sensor tests OK, check continuity of the harness from the sensor connector to the main control PCB in the top or rear control box. Repair or replace any damaged wiring.
• 6. Replace parts as needed: If the NTC is faulty, replace it with a Gram-compatible cabinet temperature sensor. If wiring and sensor are good but E1 persists, the main control PCB may be misreading the sensor and should be replaced.

When to call a technician: If you are not comfortable testing resistance or accessing the control PCB, or if a PCB replacement is required, contact an authorized Gram service technician.