Oxygen Sensor Operation

The oxygen sensor is located in the exhaust manifold. The outer surface of the sensor is in contact with exhaust gases, while the inner surface is exposed to outside air. A voltage signal, created by the difference in oxygen contents, is transmitted to the ECU. This signal is a measurement of the unburned oxygen in the exhaust gas, which is directly related to the intake air/fuel mixture. In this way, the ECU is kept up to date on air/fuel ratio so that necessary adjustments to mixture can be made.