Oxygen Sensor: Description and Operation

PURPOSE / OPERATION
The Heated Oxygen Sensor senses the oxygen concentration in exhaust gas, converts it into a voltage which is sent to the Engine Control Module. The oxygen sensor outputs about 1 volt when the air fuel ratio is richer than the theoretical ratio and outputs about 0.0 volts when the ratio is leaner (higher oxygen concentration in exhaust gas.). The Engine Control Module controls the fuel injection ratio based on this signal so that the air fuel ratio is maintained at the theoretical ratio.