Why would I need to have an OBD-II Y Cable? The first reason would be that your OBD-II port is in a location that might be in the way of the driver's legs and could damage the plug and play GPS tracker. The second reason could be that you may want to put the GPS tracker in a more secure location, but make the spare OBD-II port available for your car service. And thirdly anyone looking for a tracker in your vehicle would see a regular OBD-II plug with nothing connected to it and automatically think there was no tracker in the car.