Ice maker stops working and displays E1 on the control panel; no ice is produced.

Safety first: Unplug the ice maker from the wall outlet before opening any panels. Never work on the unit while it is connected to power.

Steps to check and address E1:

• Power reset: Unplug the unit for 10 minutes, then plug it back in and power on. If E1 clears temporarily and returns, continue with the steps below.
• Access the sensor: Remove the rear or side service panel (on most Costway countertop ice makers, the ambient sensor is clipped to the inner wall or near the air intake behind the side panel). Keep screws organized.
• Inspect the sensor wiring: Look for a small thermistor (usually a bullet-shaped or bead sensor on two thin wires) connected to the main control board. Check for pinched, cut, or burned wires and reseat the connector firmly on the board.
• Check for corrosion or moisture: If the connector is oxidized or wet, dry it thoroughly and clean light corrosion with a cotton swab and isopropyl alcohol. Allow to dry completely before reconnecting.
• Test the sensor (if you have a multimeter): Disconnect the sensor from the board and measure resistance at room temperature. A typical NTC thermistor will read between 5–50 kΩ at ~25°C. If it reads open (OL) or 0 Ω, the sensor is defective.
• Replace the sensor if faulty: Order a compatible Costway ambient temperature sensor / NTC thermistor for your exact model. Disconnect the old sensor, route the new sensor along the same path, secure it with clips or ties, and reconnect to the board.
• If E1 persists: With a known-good sensor installed, a persistent E1 usually indicates a failed main control board. At this point, replacement of the board or professional service is recommended.