Oxygen Sensor: Description and Operation

Heated Oxygen Sensor:

PURPOSE
To provide the Powertrain Control Module (PCM) with a voltage signal (input) that corresponds to changes in oxygen content of sampled exhaust gasses.

CONSTRUCTION
The two Heated Oxygen Sensors (HO2S) are threaded into the exhaust manifolds with a sampling tip extending into the exhaust stream.
The sensors have zirconium dioxide ceramic thimbles with platinum surface electrodes.

OPERATION
The ceramic thimble is oxygen ion conductive and generates voltage due to the oxygen content difference between the atmosphere and the exhaust gas. The sensor will generate a voltage signal between 0 Volts (lean condition) and 1.1 Volts (rich condition). The PCM reads this signal to achieve an air/fuel ratio of 14.7:1 when operating in CLOSED LOOP.
The HO2S sensor must operate above 600°F. To quickly heat up the sensor, a heating element is incorporated into the sensor.
The HO2S sensor will also set a fault code when the PCM determines the output signal to be out of the normal operating range.