Volkswagens have an anti-theft feature built into the radio. Every time you turn off the radio and remove the key, a red light in the face plate will start to blink: this signals that the radio is in anti-theft mode.
This is the Volkswagen VIN decoder. Every Volkswagen car has a unique identifier code called a VIN. This number contains vital information about the car, such as its manufacturer, year of production, the plant it was produced in, type of engine, model and more. CODE CALCULATOR UNLOCK YOUR RADIO FOR FREE. Honda, Opel, Chrysler, Volkswagen, Mercedes-Benz, BMW, Toyota, Nissan, Renault, Fiat, etc.
Anyone who does not know the radio code can't operate it if it is removed from the car. However, the radio also goes into this mode whenever the battery is disconnected, an electrical fuse is blown or you disconnect the radio from the current supply. You may need to reset the radio if this happens.