A diagnosis plug-in connection comprising an electrical plug connector and a mating electrical plug connector. The electrical plug connector comprises a diagnosis module with an outer conductor contact and an inner conductor contact within the outer conductor contact. The mating plug connector comprises a diagnosis head with an electrically conductive spring cage, which is designed for electrical and mechanical connection to the outer conductor contact of the diagnosis module of the plug connector. The spring cage electrically and mechanically contacts the inner conductor contact of the diagnosis module of the plug connector when the plug connector is plugged together with the mating plug connector.