Oxygen Sensor: Description and Operation

HEATED OXYGEN SENSOR (HO2S) - ZIRCONIA (Z(r) O(2))




The heated oxygen sensor (HO2S) senses the oxygen concentration in exhaust gas and converts it into a voltage that is sent to the ECU. For Zirconium type sensors, the oxygen sensor outputs about 1 V when the air fuel ratio is richer than the theoretical ratio, and outputs about 0 V when the ratio is leaner (higher oxygen concentration in exhaust gas). The ECU controls the fuel injection ratio based on this signal so that the air fuel ratio is maintained at the stoichiometric ratio. The oxygen sensor has a heating element that ensures sensor performance during all driving conditions.

HO2S - ZIRCONIA (Z(r) O(2)) OPERATION PRINCIPLE




The Zirconia (ZrO(2)) which is coated with Platinum (Pt) on both sides will generate the voltage if the density of oxygen on atmosphere side and exhaust gas side is different in high temperature.

In other words oxygen ion moves from high-density side (Atmosphere) to low-density side (exhaust gas), at a result Sensor Voltage is generated by Nearest equation between two electrodes.