There are a few reasons why you may want to detect a Global Positioning System (GPS) tracker on your car. You could be worried that you're being illegally tracked by somebody, or you might have bought a used car that has a tracker installed in it. If you're not sure whether a GPS tracker is attached to your car, you can buy a radio frequency (RF) detector and take your car to a mechanic to find out.
Go to a mechanic and have him perform a thorough search of your car's electrical wiring, mechanical parts and engine. A GPS tracker can be intricately intertwined with your car's electrical wiring and will go unnoticed to the untrained eye. Make sure to tell the mechanic that you're looking for a GPS tracker so he'll keep an eye out for anything unusual.
Thoroughly inspect the undercarriage of the car. A tracker can be attached to the wheels, axles or any pipes, crevices and seams under the vehicle. Use your hands to feel around in places that you can't see. If there is no tracker attached to the outside of the car, begin searching the inside.
Park your car in a place where it is unlikely that any other GPS signals are being sent out. Store security, traffic lights, security cameras and other cars' GPS systems can all send out signals. If you can drive to a remote campsite or around a lake or river, you shouldn't encounter any other GPS signals.
Plug the radio frequency detector into your car's power source and set it to continuously detect outgoing signals. Signals from a GPS tracker can be sent out every few seconds or every 20 minutes. The longest you likely should have wait to detect a signal is 20 minutes. That is if you turn on your RF detector right after a signal has been sent out.
Wait until the RF detector detects a signal. If no signal is detected with a half an hour, either there is no GPS tracker in your car or your RF detector isn't functioning properly. If you detect a signal, you will have to find the GPS device by hand.
Sweep the RF detector around your car until the detection signal gets stronger. This will help you find the tracking device. The problem is that you might get only one signal every 20 minutes, so finding the tracker could take a long time.
Search the entire inside of your car. A GPS tracking device could be as small as a matchbook, so you will have to check thoroughly. You may have to take apart some pieces of your car before you find the tracker. It could be in the door panels, the steering wheel column or even the dashboard. Make sure to check the seat cushions, underneath the mats and pedals, and in the boot.