A Volkswagen Polaris car with a mileage of about 90 thousand km in 2010. The user requires another one because of the loss of the key. Detection and analysis: the vehicle used fourth generation of anti-theft system, matching the anti-theft system need to use VAS5052A connection network to complete. Each key needs to be ordered in accordance with the chassis number to the manufacturer. The manufacturer preprogrammed the key, which is pre programmed with a basic code. Each key can only be applied to the designated vehicle. Only if the code is set correctly, the key can match properly.