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 driveaway 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.