I think trader4 made a good suggestion which would be to 'listen' to the car. As in, go for a drive, pull it into a garage at night and just listen to see if you can hear anything whirring away. Just remember these cars take up to 20mins to fully go to 'sleep', so if something persists beyond that.....

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2005 3.0d Sport - Sapphire Black
Engine : Bluefin Superchip Tune,
Wheels & Sus: Style 168s (10.5s all round), H&R RDA Spacers, Bilstein B12, Eibach 40mm drop, Whiteline RSB
Exterior: Le Mans flares, 4.6is kit F&R
Interior: Dynavin N6, Blackvue DR650 dash cams

My Build Thread: http://www.xoutpost.com/bmw-sav-foru...run-sheet.html