The possible reasons for the failure of the car usb interface are: 1. The USB interface is broken. 2. The vehicle USB interface fuse is burnt out. 2. There is a problem with the charging cable. 3, there is a problem with the phone interface. You can check which is the problem one by one, usually there are more reasons for the line. You can also go to the repair shop to check the specific reasons. I hope my answer can help you.