Hi boet. Failed crank sensor would cause non start.
Failed cam sensor would cause poor or rich running.
Crank sensor can be tested with a multimeter. IIRC it should be around 540 ohm.
Cam sensor is a hall effect and resistance cannot be tested
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Or alternatively check this. More info
http://www.bimmerforums.com/forum/showthread.php?t=1690962
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