Heated Oxygen Sensor

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

The HO2S produces low voltage (less than 0.4 volt) to indicate a lean mixture (high amount of oxygen) and a high voltage (more than 0.6 volt) to indicate a rich mixture (low amount of oxygen). This voltage signal is transmitted to the PCM. All models use more than one sensor.