Oxygen Sensor: Description and Operation

HEATED OXYGEN SENSOR (HO2S) - SINGLE HO2S
The heated oxygen sensor senses the oxygen concentration in the exhaust gas, then converts it into a voltage and then sends this to the ECM. The heated oxygen sensor gives an output of about 800 mV when the air fuel ratio is richer than the theoretical ratio and output of about 100 mV when the ratio is leaner (higher oxygen concentration in exhaust gas.) The ECM controls fuel injection based on this signal so that the air fuel ratio is maintained at the theoretical ratio.