Disconnect the cable from the negative battery terminal. For four-cylinder models, the CMP sensors are located at the top corners of the valve cover, above the left end of the intake and exhaust camshafts. Remove the air filter outlet duct, then disconnect the CMP sensor electrical connector. Next, remove the CMP sensor mounting bolt and take the sensor out from the valve cover. Inspect the condition of the CMP sensor O-ring; if it is cracked, torn, or deteriorated, replace it. Installation is the reverse of removal. For V6 models, on 3.0L engines, a single CMP sensor is located above and to the left of the air conditioning compressor on the front bank cylinder head. On 3.5 non-VCT engines (2008 through 2012 models), there are two CMP sensors located at the ends of each cylinder head on the driver's side. For 3.5L VCT (variable cam timing) engines (2013 and later models), there are four CMP sensors, two on the end of each cylinder head. If working on a 2008 or later model, remove the air filter housing and duct, then disconnect the CMP sensor electrical connector(s). Remove the mounting bolt(s) and take out the sensor(s). Remove the CMP sensor O-ring and inspect its condition; if it is cracked, torn, or otherwise deteriorated, replace it. Lubricate the sensor O-ring with clean engine oil, and installation is otherwise the reverse of removal. Tighten the CMP sensor mounting bolt to the specified torque.