One problem related to cooling fan has been reported for the 2003 BMW 530. The most recently reported issues are listed below.
My 4 month old 2003 BMW 530ia spontaneously caught on fire starting in the engine compartment while sitting out on my driveway next to my house. The car was totaled. The car was not running and had been off for 3. 5 hours. BMW 5 series cars had fires just like this one in 2001 models and BMW issued a recall notice at that time because of a faulty auxiliary cooling fan switch. They are refusing to take any official responsibility for this incident even thought their rep, jerry gasparrini told me over the phone that the problem was probably the same type of problem that occurred in 2001 based on their engineer's assessment. This could have resulted in my house burning down and possibly also fatalities. We were lucky. This company needs to be investigated and the responsible supplier needs to be smacked down good and fined heavily.