Oxygen Sensor

This unit is positioned in the exhaust manifold so it can sense exhaust gas composition as it comes from the engine. The sensor detects oxygen content in order to relay a signal to the ECM. This sensor is actually a (Zirconia) battery which reacts to oxygen levels by generating a voltage signal (100 to 900 millivolts) that is inversely proportionate to the amount of oxygen. If the oxygen content of exhaust gas is high (indicating a lean mixture), the voltage signal created by the sensor will be low. If oxygen content is low (indicating a rich mixture), the voltage signal to the ECM is high. The oxygen sensor should be replaced every 30, 000 miles to ensure proper function.