Oxygen Sensor: Description and Operation

OPERATION
The heated oxygen sensor functions to detect the concentration of oxygen in the exhaust gas; it converts those data to voltage, and inputs the resulting signals to the engine control module.

If the air/fuel mixture ratio is richer than the theoretical air/fuel mixture ratio (i.e., if the concentration of oxygen in the exhaust gas is sparse), a voltage of approximately 1V is output; if the air/fuel mixture ratio is leaner than the theoretical air/fuel mixture ratio (i.e., if the concentration is dense), a voltage of approximately 0V is output.

The engine control module, based upon those signals, regulates the amount of fuel injection so that the air/fuel mixture ratio becomes the theoretical air/fuel mixture ratio.

Battery power supply is applied, by way of the Multiport Fuel Injection (MFI) relay, to the heated oxygen sensor heater. As a result, the sensor element is heated by the heater, so that the heated oxygen sensor shows excellent response even if the temperature of the exhaust gas is low.