Identify the claimed equipment
Ask whether the car has a rear camera, additional camera views, parking sensors or a parking assistance function. These are different features. A parking screen does not establish that every one of them is fitted.
Use a safe demonstration
Follow the vehicle's instructions and keep the area clear. Ask the seller to demonstrate the display and controls with the car safely secured. Do not place a person behind or beside a moving car to test detection, and do not create obstacles for a system to avoid.
Inspect what you can see
Look for damaged or obscured camera lenses and sensor areas without taking anything apart. On the display, note whether the expected views appear and whether warnings are shown. A clear image is useful, but it does not prove that every part of a parking system is correctly aligned or functioning.
Keep the result modest
Record which views you saw and which functions remain untested. Ask about repairs around the cameras, bumpers or related equipment if there is a concern. A qualified workshop can investigate faults or calibration questions. Even when a demonstration looks convincing, parking aids do not replace looking around the vehicle and taking responsibility for its movement.