A car stereo code is an anti-theft feature implemented by many of the major automobile manufacturers. When a car stereo is disconnected, it is rendered unusable until the user enters the proper security code. Some cars also require the code if the battery runs out of power.
The car stereo code is usually located in the user's manual or on the stereo manufacturer's website. Owners can also call their local car dealer for the security code. The process for entering the car stereo code depends on the unit's manufacturer and model. The most common procedure involves using the tuner or volume knobs to select numbers before pushing the knob to enter the code.