Ice maker shows F21, ice compartment too warm, ice melts and refreezes into clumps

Safety: Disconnect power before accessing sensors or control boards.

• Locate sensor: The ice compartment sensor is usually clipped to the liner or evaporator. Refer to the service diagram if available.
• Visual inspection: Check for broken wires, corrosion at the connector, or a sensor that has come loose from its mounting point.
• Resistance test: Disconnect the sensor and measure its resistance at room temperature and in ice water. Compare readings to Miele's NTC chart. Replace if readings are out of range or unstable.
• Harness continuity: If the sensor tests good, check continuity from the sensor connector back to the control board. Repair any broken wires.
• Control board: If sensor and wiring are good but F21 remains, the main control board may be defective and require replacement.

Note: After replacing a sensor, clear the error by disconnecting power for 5 minutes.