Oxygen Sensor: Description and Operation

The heated oxygen sensor (O2 sensor), located in the rear exhaust manifold, provides an input voltage to the Single Board Engine Controller (SBEC). The oxygen sensor is a voltage generating device. A voltage signal (0-1 volt) is generated by the difference in oxygen content between the exhaust gases and outside air. The higher the difference (rich mixture, low exhaust oxygen content) the higher the voltage generated by the oxygen sensor. Smaller differences (lean mixture, high exhaust oxygen content) result in a lower voltage generation. The SBEC uses the voltage signal for information about the air/fuel ratio being delivered to the engine.

The oxygen sensor has a heating element that maintains proper oxygen sensor operating temperature at all times. This process allows the vehicle to enter CLOSED loop at an earlier time and to remain in CLOSED loop during the remainder of the operating cycle. The oxygen sensor heating element receives voltage from the automatic shutdown (ASD) relay.