Abstract: A motor-vehicle control unit having an electrical circuit on a support, which may be a printed circuit board or metal plate with stamped conductors. The motor-vehicle control unit includes a plug-in body encasing components of the electrical circuit and is formed with at least two side surfaces. The plug-in body is received in a receptacle of a motor vehicle. The support protrudes beyond the at least two side faces of the plug-in body and engages groove shaped recesses in the receptacle for guidance of the unit into the receptacle. The plug-in body may be formed of curable foam and the flanges may be formed with recesses for engaging spring tabs.