One problem related to check engine light on has been reported for the 2000 BMW 528. The most recently reported issues are listed below.
2000 BMW 528 idles rough in cold climates (2002/2003). This produces no check engine lights. The problem goes away once the car is warmed up or in warmer climates. Dealer constantly states "problem unreproducable". After numerous visits I left the car overnight at dealership and the following morning went back, grabbed a technician and had him sit in the car with me. Afterwards technician said it's probably a part called the vanos unit. Had part replaced then problem went away. This winter (2003/2004), problem resurfaced.