The crank position sensor sits directly above the bell housing, behind the engine. If by check it you mean test it, well, as far as I know you can only test by replacement with a known good unit. If the band near the connector end is yellow, it needs to be, or will eventually need to be replaced. The insulation on the yellow banded ones fail and the sensor subsequently also fails. Why do you suspect it is faulty? Becareful when removing the CPS, the aluminum housing is VERY fragile and can easily break. I cracked my housing when trying to remove it and had to drop the tranny to replace the housing bracket(that's the only way). However, once I replaced it, the car ran like a totally different car.