An electrical plug-in connector for interconnecting contacts of a first contact carrier and of a second contact carrier includes: an electrical connector element that is inserted in a chamber in a housing body when in an inserted position, such that the electrical connector element forms, on a first connection side of the housing body, a first electrical contact portion for plug-in connection to the contact of the first contact carrier and, on a second connection side of the housing body, a second electrical contact portion for connection to the contact of the second contact carrier. The electrical connector element is inserted at least in portions into the chamber via a side insertion opening when in the inserted position. The electrical connector element includes at least one clamping slot for being held on the housing body, which slot is open towards an outer edge of the electrical connector element.