A plug connector, in particular a high current plug, having a locking device for the play-free axial fixing of the plug connector with respect to a mating plug connector in a closed position coupled to the mating plug connector, wherein the locking device has a retaining element such as a latching clip to engage axially behind a locking projection on the mating plug connector in the closed position, and a mating pressure element which is located opposite the retaining element in such a way that the locking projection can be accommodated between the retaining element and the mating pressure element in the closed position. An actuating device for pressing on retaining element and/or mating pressure element is formed on the locking projection in a fixing position (II).