Oxygen Sensor: Description and Operation

Oxygen Sensor:

PURPOSE
The oxygen (02) sensor detects the amount of oxygen in the exhaust gas compared to the outside air and sends a voltage signal to the Engine Control Module (ECM).

CONSTRUCTION
The sensor has a closed-end tube made of ceramic zirconia.

OPERATION
The differences in oxygen content between the exhaust gas and the atmosphere make the sensor generate a voltage signal. The zirconia generates voltage from approximately 1V in richer conditions to 0V in leaner conditions.

- A richer A/F mixture equals higher voltage (Approx. 1 volt).
- A leaner A/F mixture equals a lower voltage (Approx 0.1 volt).

The ECM interprets the voltages and number of voltage "swings" (cross-counts) and will vary injector open times to control the air-fuel ratio.