Handle the ECT sensor with care, as damage will affect the operation of the entire fuel injection system. Begin by disconnecting the cable from the negative battery terminal and partially draining the cooling system. For four-cylinder models, the ECT sensor is located on the back side of the cylinder head; remove the spring clip and pull the sensor from the coolant temperature control housing, then reinstall by reversing the removal process and refilling the cooling system. In V6 models, the ECT sensor is positioned at the driver's end of the engine for 2006 and earlier models, and at the back for 2007 and later models. For 2011 V6 models, remove the air filler housing, disconnect the electrical connector to the ECT sensor, and unscrew the sensor from the cylinder head. Avoid sealing the threads of the new sensor with Teflon tape, as it will interfere with grounding; instead, apply a small amount of liquid sealer to the threads before installation. Reinstall the sensor by reversing the removal steps and ensure it is tightened securely before refilling the cooling system.