An operatively automatic magnetic open door retainer for motor vehicle conveyance components, as for example semi-trailers. A representative system includes a database system operable to store a plurality of network profiles, each network profile being associated with a user. The additional air mass is compensated by the lambda regulation by means of an increase in the value of the control signal, in such a way that the likewise increased value of the evaluation signal can be used for identifying leaks in the intake port.