2005 nissan altima crankshaft position sensor connector

The crankshaft position sensor is attached to the engine block facing the timing rotor on the crankshaft. It counts the number of teeth on the crankshaft that have passed the sensor, sending this value to the ECU which can then work out where the crankshaft is on its 360-degree rotation.

The crankshaft position sensor is the most important of all engine management sensors, and the engine will absolutely not run without it.