Digital Costway freezer displays E1 and interior temperature is not accurate or fluctuates wildly.

Safety first: Unplug the freezer from the wall outlet before removing any panels or touching wiring. Do not work on the unit while it is energized.

Steps to check and address E1:

• Power reset: Unplug the freezer for 5 minutes, then plug it back in to see if the code clears. If E1 returns, continue.
• Locate the cabinet sensor: On most Costway freezers, the temperature sensor (NTC) is clipped to the evaporator tubing behind the interior rear panel or mounted on the liner wall near the evaporator.
• Inspect the sensor and wiring: Remove the interior shelves and the rear inner panel (usually a few Phillips screws). Look for a small probe with two wires. Check for broken insulation, pinched wires, or corrosion at the connector.
• Test the sensor (if you have a multimeter): Disconnect the sensor from the harness. Measure resistance at room temperature; most NTC sensors will read between 5 kΩ and 20 kΩ at ~25°C. If it reads 0 Ω (short) or OL (open), the sensor is faulty.
• Check the harness: Follow the sensor wires to the main control board (usually behind a rear lower access panel). Ensure the plug is fully seated and not corroded or burnt.
• Replace the sensor: If damaged or out of spec, install a compatible Costway freezer NTC sensor. Route the new sensor along the original path, secure it with clips or tape, and reconnect to the control board.
• Reassemble and test: Reinstall the interior panel and shelves, restore power, and monitor if E1 clears and temperature stabilizes over several hours.

When to call a technician: If the sensor and wiring test good but E1 persists, the main control board may be misreading the sensor and should be diagnosed by a professional.