Oxygen Sensor: Description and Operation

Fig. 57 O2 Sensor:

The oxygen (O2) sensor, which is mounted in the exhaust flow, monitors the amount of oxygen in the exhaust gas. The electrical resistance of the ceramic titania, of which the sensor is made of, changes drastically at the ideal A/F mixture. The ECU supplies the sensor with a 1 volt reference signal then measures the amount of voltage passing through the sensor to determine at what A/F mixture the engine is operating at. The sensor is also equipped with a heating element. This allows the sensor to operating sooner than it would if it had to rely simply on exhaust gas temperature to heat it.

O2 Sensor Operation:

Refer to the chart for O2 sensor operation.