Whynter ice maker displays E4 and stops, often after running briefly

Safety: Disconnect power before working inside the ice bin area.

Steps to fix E4:

• Empty the ice bin: Remove all ice from the storage bin and ensure nothing is blocking the ice-full sensor or arm.
• Identify sensor type: Some Whynter models use an infrared (IR) sensor pair; others use a mechanical arm. Locate the sensor on the side of the bin or the arm above the bin.
• Clean optical sensors: If IR sensors are used, gently clean the emitter and receiver windows with a soft cloth and mild glass cleaner. Dust or frost can cause false "bin full" readings.
• Check arm movement: For mechanical arms, move the arm up and down. It should move freely and return to its rest position. If it is stuck in the up (full) position, clear obstructions and ensure the pivot is not jammed.
• Inspect wiring: Follow the sensor wires back to the control board. Reseat connectors and check for broken wires.
• Test sensor (if accessible): For IR sensors, you can check for voltage at the sensor board according to the service manual. If there is power but no change when ice is present/absent, replace the ice-full sensor assembly.
• Re-test: Restore power and run the unit with an empty bin to confirm that E4 is cleared and the unit resumes ice production.