Oxygen Sensor: Description and Operation

Oxygen Sensor:

Oxygen Sensor Operation:

The oxygen sensor generates voltage according to exhaust gas oxygen content. It incorporates a platinum coated ceramic zirconia tube which generates voltage if there is a difference in oxygen concentration between the inside and outside of the tube. The voltage range is approximately 0.1-1.0V. Voltage increases when oxygen content is low (rich) and decreases when oxygen content is high (lean). The ECU determines air/fuel ratio based on the voltage generated and makes appropriate adjustments to maintain the optimum ratio of 14.7:1. The difference in oxygen concentration changes greatly in the area of optimum air/fuel ratio, resulting in large voltage changes that are easily calculated by the ECU. To operate at peak efficiency, the oxygen sensor must heat up to approximately 300 - 400°C (572 - 752°F).

The oxygen sensor is equipped with an ECU controlled heating element to quickly warm it up to operating temperature. At cold start and drive-away at part throttle, the ECU energizes the sensor heating element for up to two minutes. The ECU performs this function when ambient air temperature is below 10 - 16°C (50 - 60°F) and engine speed is below 2250 rpm.