Oxygen Sensor: Description and Operation

Exhaust Gas Oxygen (EGO) Sensor:

Oxygen Sensor Operation:

PURPOSE
Measures oxygen content of exhaust gas and sends a voltage signal to the Powertrain Control Module (PCM). PCM determines air/fuel ratio based on voltage generated and makes appropriate adjustments to maintain the optimum ratio of 14.7:1.

OPERATION
Sensors generate voltage according to exhaust gas oxygen content. Voltage range is approximately 0.1-1.0 Volts. Voltage increases when oxygen content is low (rich) and decreases when oxygen content is high (lean). 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 PCM. To operate at peak efficiency, oxygen sensor must heat up to approximately 572-752°F (300-400°C).

CONSTRUCTION
Sensors incorporate a platinum coated ceramic zirconia tube that generates voltage if there is a difference in oxygen concentration between inside (exhaust gas stream) and outside (fresh air) of tube.