Whenever the crankshaft sensor is replaced, then the crankshaft pulley is changed, the crankshaft is changed or the engine is pulled out of the vehicle, then the PCM must be re calibrated by a scanner. An electrical crankshaft sensor variation relearn requires one to use a TECH-2 scan tool and the PCM must be reflashed by a dealer service department or any qualified automotive shop. For four-cylinder models, the CKP sensor is mounted on the front of the engine block at a distance from the starter. Start by lifting the front of the vehicles and placing it on jackstands and then proceed to remove the starter motor. Remove the cable-tethered electrical connector from the CKP sensor, loosen the mounting bolt of the sensor and pull the sensor out. However, if reusing the old CKP sensor, then always take out the former and install a new O-ring. As will be seen during removal, installation is in the reverse order to that shown above and the mounting bolt is tightened. In the 3.5L and 3.9L V6 models, the CKP sensor is fitted to the back side of the engine block. Following lifting of the vehicle and ensuring it stays in the requisite position you need to: Unplug the electrical connection, pull out the mounting bolt, and dispose the old O-ring. As with removal, installation is the complete opposite, employing a new O-ring and torquing the bolt to a precise value appropriately termed. For 3.6L V6 models, then, lift the vehicle and secure it on jackstands, as well as unscrew the heat shield of the lower part of the rear exhaust manifold, further, unscrew the electrical connector of the sensor in addition to the sensor mounting bolt to remove the sensor from the block. As mentioned before, installation is the mirror image of removal which means to use a new O-ring and tighten the bolt well.