A connector (1) impermeable to liquids, having two matching connector parts (3) and (5), which is sealed in a connected position by at least one peripherally extending circumferential sealing ring (6) provided between the connector pats (3) and (5). The plug-in position is secured by a rotatable, axially fixed threaded bushing (8), which is fixed in the axial direction, but rotatably supported on one of the connector parts, and the internal thread (9) of which is mated to the holding thread (10) on the other connector part. A further thread or projection or threaded part (12) mating with the interior thread (9) is provided in a loosening direction at a distance from the holding thread (10) interacting with the threaded bushing (8), and a distance A from the end of the holding thread (10) to that of the further thread (12) is greater than a plug-in depth of the connecting pins (2) into the bushings (4). The sealing ring (6) for both connector parts is disposed at a location at which it is still in the sealing position after pulling back the threaded bushing (8) that is detached from the holding thread (10). Any sparks occurring upon loosening of the contacts are therefore shielded from the environment.