An oxygen sensor functions as a galvanic battery that generates a small voltage output based on the oxygen levels in exhaust gases, providing essential input for the feedback loop with the Powertrain Control Module (PCM) to maintain the ideal air/fuel ratio of 14.7:1 for optimal
Catalytic Converter performance. Vehicles equipped with On-Board Diagnostics II (OBD-II) utilize two oxygen sensors-one before and one after the catalytic converter-to assess converter efficiency by comparing oxygen levels in the exhaust gases. Four-cylinder models feature one upstream and one downstream heated oxygen sensor, while V6 models have four heated sensors, with two for each cylinder head and multiple catalysts. All sensors are heated to improve warm-up time, and care must be taken during servicing to avoid damaging the permanently attached pigtail and electrical connector, keeping contaminants away, and ensuring proper installation of the silicone boot. When replacing an oxygen sensor, it is advisable to warm the engine to ease removal, disconnect the electrical connectors, and use an oxygen sensor socket for unscrewing. Anti-seize compound should be applied to the threads of old sensors, while new sensors come pre-coated. Installation follows the reverse order of removal, ensuring proper torque is applied.