Oxygen Sensor: Description and Operation
Heated Oxygen SensorOxygen Sensor Ideal Mixture Ratio Chart:
Heated Oxygen Sensor (HO2S):
The Heated Oxygen Sensor (HO2S) is located in the exhaust tube. It detects the amount of oxygen in the exhaust gas compared to the outside air. The heated oxygen sensor has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from approximately 1 Volt in richer conditions to 0 Volts in leaner conditions. The heated oxygen sensor signal is sent to the ECM. The ECM adjusts the injection pulse duration to achieve the ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical change from 1 Volt to 0 Volts. A heater is used to activate the sensor.