All gasoline models discussed here are equipped with On-Board Diagnostics II (OBD-II) engine management systems, allowing them to verify the feedback loop between the oxygen sensor and the PCM. This is achieved by using an oxygen sensor before and after the catalytic converter. This system enables the PCM to gauge the converter's efficiency and even predict potential failures. The primary (upstream) oxygen sensor is situated in the exhaust manifold, and the secondary (downstream) one is behind the catalytic converter. Both these sensors are heated. Special attention is required when servicing a sensor. Ensure that the permanently attached pigtail and electrical connector remain intact, avoid contaminants on the sensor, never use cleaning solvents on it, handle it with care, and ensure the silicone boot is correctly positioned. When replacing an oxygen sensor, given its location in the contracting exhaust manifold or pipe, it might be hard to loosen when cold. To prevent damage, briefly run the engine before proceeding. Ensure the ignition is OFF. If working on a V10 model, elevate the vehicle safely. Disconnect the oxygen sensor harness, then unplug its electrical connector. On V8 models, the sensor can be accessed without lifting the vehicle. Simply unplug its connector. Unscrew the sensor using a special slotted socket, especially if reusing it. When reinstalling, apply anti-seize compound to the threads to make future removal easier. After securing the sensor, reconnect the electrical connector and, if the vehicle was elevated, lower it. Finally, test drive to ensure no trouble codes have been activated.
