For BMWs Manufactured in 2000 and After
1. Insert your key into the ignition but make sure it is in the "Off" position.
2. Locate the “M” button. In some BMWs the ”M” button will be between two arrows, one facing left and the other facing right. The "M" button is on the front of the BMW business radio with the other radio control buttons.
3. Press and hold the "M" button while turning the key. Only turn the key to turn on the radio, but do not start the car.
4. Look for the serial number on your radio display. The serial number should flash across the screen. It will not disappear unless you press other buttons on the radio to access the menu.
For 1999 and Older BMWs
5. Remove the radio unit from the chassis to view your serial number for model year vehicles 1999 and older.
6. Locate a resource or professional to properly remove the radio unit from your vehicle. The procedure for removing the radio may be slightly different, therefore, find specific instructions for your year and model. Research various sites online that will give you step-by-step instructions for removing your audio system properly to retrieve your serial number.
7. Look on the back of the chassis of your radio to locate your serial number. Your serial number will start with either "F, Pha, P, BP or AL."