Oxygen Sensor: Description and Operation

HEATED OXYGEN SENSOR (HO2S)

SOHC Engine Is Shown, DOHC Locations Are Similar:

The heated oxygen senor senses the oxygen concentration in exhaust gas, converts it into a voltage which is sent to the ECM. The heated oxygen sensor outputs about 800mV when the air fuel ratio is richer than the theoretical ratio and outputs about 100mV 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. The oxygen sensor has a heater element which ensures the sensor performance during all driving condition.