Digital Igloo upright freezer beeps and displays E1; temperature reading is missing or shows dashes; compressor may not start.

Safety first: Unplug the freezer before removing panels or handling wiring. Use insulated tools and avoid working on a wet floor.

Step-by-step checks:

• Power cycle the unit: Unplug the freezer for 5 minutes, then plug it back in. If E1 returns immediately, continue with diagnosis.
• Locate the cabinet thermistor: On most Igloo uprights, the temperature sensor is behind a small plastic cover on the interior back wall or near the evaporator cover. Remove the cover carefully.
• Inspect the sensor and wiring: Look for broken insulation, pinched wires, or corrosion at the connector. Reseat the connector firmly at both the sensor and the main control board (usually behind the top or rear control panel).
• Test the thermistor: With the freezer unplugged, disconnect the thermistor and measure resistance with a multimeter. At room temperature (around 77°F / 25°C), most Igloo NTC thermistors read roughly 5k–10k ohms. If the reading is infinite (open) or near 0 ohms (short), the sensor is faulty.
• Replace if defective: If readings are out of spec, replace the cabinet temperature sensor with an Igloo-compatible thermistor kit. Route the new sensor along the original path and secure it away from moving parts or sharp edges.
• Reassemble and test: Reinstall covers, restore power, and confirm that the display now shows a valid temperature and the E1 code clears after a few minutes.

When to call a technician: If the thermistor tests good but E1 persists, the main control board may be defective and should be diagnosed or replaced by a professional.