The knock sensor is located on the rear of the engine block, directly below the cylinder head. To replace it, first relieve the fuel system pressure, then disconnect the cable from the negative battery terminal. Next, drain the cooling system and remove the intake manifold to access the sensor. Disconnect the electrical connector, unscrew the mounting bolt, and remove the sensor. When installing the new knock sensor, ensure it is aligned parallel to the engine block, with the connector at no more than a 7-degree angle from a horizontal plane, and tighten the mounting bolt to 15 ft-lbs (20 Nm). Avoid overtightening to prevent damage, and complete the installation in reverse order. For testing, disconnect the knock sensor connector and use a Digital Volt Ohm Meter (DVOM) set to measure resistance between the two terminals of the knock sensor; with the engine cold (68 degrees-F), the resistance should be between 120k and 280k ohms.