Can a 4S shop detect whether there is a monitor in the vehicle?

[Aaliyah]

Can a 4S shop detect whether there is a monitor in the vehicle; Types of monitors: strong magnetic non-installation type, wiring type, OBD interface type, how to find the monitor in the car: directly search for hidden places in the car, such as near the front and rear bumpers, inside the left and right doors, etc., but this also makes these so-called hidden places actually become commonly known secret locations. Use a magnetic field signal strength sensing device to find it, use an old-fashioned FM radio, talk while tuning the frequency, listen to whether there is an echo in the radio, check the lines, in order to find the monitor, you can search along the power line of the car. However, this requires more professional staff, otherwise you may not know the location of the power line.