Abstract: A system for the read-out of vehicle data via a diagnostic port, specifically an OBD plug connection of a vehicle, including a connector unit for a diagnostic port of a vehicle, and a gateway apparatus for communication with an air-conditioning installation of the vehicle, specifically a parking heater, wherein the connector unit, specifically the OBD plug connection, includes a connector body, having a plug-in side with first contacts for connection with the diagnostic port, and a connection side with second contacts, specifically for connection with a diagnostic device, and at least one branch feeder, wherein the branch feeder is brought out of the connector body from at least one of the first contacts, and is communicatively connected to the gateway apparatus.