Three problems related to alternator/generator/regulator have been reported for the 2002 BMW 325. The most recently reported issues are listed below.
Battery and alternator checked good with various service providers yet vehicle had a persistent battery drain witch would only appear after car was on the road and driving. After car stopped running due to low battery it then would not restart. No warning lights would come on until just a minute or two prior to engine quitting. Took vehicle to monrovia BMW in monrovia CA and was told that alternator was faulty. Installed new (not rebuilt) specified alternator and new battery and 5 months later same problem came back. Further own personal investigation found that BMW is aware of a faulty electrical system design flaw and I was never told about from BMW tech's at time of inspection as to the possibility of a system problem when the climate control "blower motor resistor" of "final stage unit" (fsu) and its internal resistor fails. This part has hundreds of write ups online from other owners and has gone back many years. When the part fails it leads to a whole variety of electrical problems with the affected vehicle. This could lead to a full engine shut down and lead to a crash. My vehicle has also been experiencing loss of engine coils and these are also part of the electrical system that could be being impacted by this fsu / resistor problem. Fire and or other electrical problems are also possible.
Rear right window came off the track and broke window regulator. Replaced window regulator. Technician remarked that both front windows are moving slowly so will need to be replaced soon also.
Battery was replaced a few weeks ago but it went dead again. Took that car back to the dealership. The dealership technician found an open circuit in alternator. Replaced alternator.