Oxygen Sensor: Description and Operation

PURPOSE/OPERATION





The Heated Oxygen Sensor (HO2S) senses the oxygen concentration in exhaust gas converts it into a voltage which is sent to the Engine Control Module (ECM). The heated oxygen sensor outputs about 800 mV when the air fuel ratio is richer than the theoretical ratio and outputs about 100 mV when the ratio is leaner (higher oxygen concentration in exhaust gas.) The ECM controls the fuel injection ratio based on this signal so that the air fuel ratio is maintained at the theoretical ratio.