Oxygen Sensor: Description and Operation

Heated Oxygen Sensor:

PURPOSE/OPERATION
The oxygen sensor measures the oxygen content in the exhaust and sends a voltage signal to the ECM. This sensor produces a measureable voltage by comparing the amount of oxygen in the exhaust gas with the amount in the ambient air. The sensor operates only within a certain temperature range of approximately 285 - 850°C (545 - 1530°F). The exhaust gases reach the outer surface of the oxygen sensor tip via the openings in the protective sleeve. Ambient air reaches the sensor's inner surface via channels. The difference in oxygen content produces a voltage read by the ECM. A heater is provided to allow the sensor to reach operating temperature faster, allowing ECM control of the A/F mixture sooner. The heater warms the sensor up faster than if it had to rely simply on exhaust gas heat. The MPFI system then controls the A/F mixture sooner, reducing exhaust emissions.