Oxygen Sensor: Description and Operation

Description

Heated Oxygen Sensor (HO2S) consists of zirconium and alumina and is installed on upstream and downstream of the Manifold Catalytic Converter (MCC).
After it compares oxygen consistency of the atmosphere with the exhaust gas, it transfers the corresponding voltage signal to the ECM. When A/F ratio is rich or lean, it generates approximately +1V or 0V respectively.
In order that this sensor normally operates, the temperature of the sensor tip must be higher than predetermined temperature. So it has a heater which is controlled by the ECM duty signal. When the exhaust gas temperature is lower than the specified value, the heater warms the sensor tip.