A housing cap comprises: a cap basic body having a cap floor having an opening as well as a surrounding cap lateral wall adjoining an edge of the cap floor. A window pane of a transparent material placed on a side of the cap floor facing toward the cap lateral wall in a manner sealing the opening of the cap floor; as well as a contact disk placed on a side of the window pane facing away from the cap floor. The cap lateral wall includes on an inner side facing the window pane a groove, while the contact disk has a contact region bearing against the window pane as well as an outer edge having formed therein a plurality of teeth, which are in engagement with the groove.