The crankshaft position sensor is under the intake manifold and starter motor, on the engine block's left rear. Ensure the ignition is OFF before starting. Raise and safely support the car. Disconnect the sensor harness connector and remove the sensor from the block, catching any oil drips. To install, reverse these steps. Use a new sealing o-ring, replace the bolt, and route the wiring as before. Clear any ECM fault codes post-installation.