Neck Warmer Not Working. The neck warmer function (NWR) is not working and the LEDs in the NWR control element do not light up. The neck warmer functions properly after switching the ignition off and on again. The control unit is located under the rear seat bottom, as shown in the photo, and is clipped into place.SMFA (Seat Module Drivers) fault code E44C21: "LIN bus: Neck warmer control unit does not function" is stored. Note: For the first time, the neck warmer is available as optional equipment (SA4NH) in the Convertible. The neck warmer reduces cold drafts that a customer feels on his or her neck when driving with the roof open. Warm air is guided over the seat. The operation differs depending on whether the roof is open or closed. Neck warmer software application error.
