Miele Washer Error Code F4025

Error code F4025 on a Miele washer indicates that the control board has detected an impermissibly low resistance value at the NTC (Negative Temperature Coefficient) temperature sensor circuit. NTC sensors work on the principle that their electrical resistance decreases as temperature rises. When the control registers a value that falls below the acceptable minimum threshold, it interprets this as a fault condition and halts operation. An abnormally low resistance reading typically points to a short circuit somewhere in the sensor itself or in the wiring harness connecting the sensor to the control board.

The NTC temperature sensor is a critical component in the wash system. It monitors water temperature throughout the cycle and feeds real-time data to the control board, which uses that information to regulate the heating element and ensure accurate cycle temperatures. If the sensor or its leads are shorted, the control board receives a signal indicating an impossibly low resistance, which could be misinterpreted as an extremely high temperature reading, prompting the machine to shut down as a safety precaution.

The two primary causes of F4025 are a failed NTC sensor with an internal short circuit, and damaged or pinched wiring between the sensor and the control board. Moisture ingress, mechanical wear, and heat exposure over time can all degrade both the sensor element and its associated wiring. Diagnosing this fault requires a multimeter to measure resistance across the sensor terminals and continuity testing along the sensor leads to isolate whether the short originates in the sensor body itself or in the connecting harness.