Contrary to some existing information, the BMW 3-series was never offered with the DSP option. Most people confuse the speaker icon on the center console of factory systems as the button for DSP. This is only an "imaging" button and not the DSP option.

In late 2002, BMW switched the configuration slightly and removed the coaxial input cable from the factory CD Changer and reverted the CD changer connections back to the 3-pin/6-pin design for an analog signal - this is what is referred to as "analog DSP". For vehicles manufactured after mid-year 2002, you will have to inspect the CD changer connections to determine what type of DSP is present.

If the vehicle is equipped with a CD Changer, this is simple as you will be able to check what connections are plugged into your changer. If the vehicle is not equipped with a CD, you will need to locate the factory amplifier and inspect to see if a coaxial cable is present.