Heated Oxygen Sensor (HO2S)

At operating temperature, Heated Oxygen Sensor (HO2S) monitors oxygen content of exhaust gases. A heating element is used to warm HO2S to operating temperature, enabling faster conversion of feedback system to closed loop operation.

HO2S produces low voltage (less than .4 volt) to indicate lean mixture (high amount of oxygen) and a high voltage (more than .6 volt) to indicate rich mixture (low amount of oxygen). This voltage signal is transmitted to PCM. All models use more than one sensor.