When servicing an oxygen sensor, it is important to note that due to its installation in the exhaust manifold or pipe, it may be difficult to loosen when the engine is cold; therefore, starting and running the engine briefly can help. Care should be taken to avoid damaging the permanently attached pigtail and electrical connector, as any damage will render the sensor useless. Keep contaminants away from the electrical connector and the louvered end, and do not use cleaning solvents on the sensor, which is delicate and should not be dropped or handled roughly. Ensure the silicone boot is correctly positioned to prevent melting. For replacement, raise the vehicle securely on jackstands. In 2003 and earlier models, the upstream sensor is located behind the exhaust pipe "Y" junction and ahead of the
Catalytic Converter, while the downstream sensor is screwed into the catalyst. Disconnect the electrical connector for the upstream sensor, remove it using a wrench, and apply anti-seize compound if reinstalling the old sensor; new sensors do not require this. The installation follows the reverse order, ensuring proper torque. For 2004 and later models, the upstream sensors are at the cylinder heads above the warm-up catalysts. After removing the engine cover, disconnect the electrical connector, use an oxygen sensor socket for removal, and apply anti-seize compound if reinstalling the old sensor. The installation is again the reverse of removal. For downstream sensors in these models, raise the vehicle, remove the engine under cover, locate and disconnect the electrical connector, and follow the same procedures for removal and installation, ensuring proper torque.