DeVille V8-4.9L VIN B (1995)
Oxygen Sensor: Description and Operation
Oxygen Sensor Location
Two oxygen sensors are mounted in the exhaust system where they monitor the oxygen content in the exhaust stream. There is a sensor mounted in each
exhaust manifold. An oxygen sensor acts like a battery because it creates its own signal voltage once it reaches operating temperature. This voltage is
produced when the oxygen content in the exhaust stream is different than the oxygen content in the atmosphere. A lean condition (high oxygen content in
exhaust) will produce a low voltage (near 0 volt) and a rich condition (low oxygen content in exhaust) will produce a high voltage (near one volt). The
Powertrain Control Module (PCM) provides a reference signal voltage (0.45 volt) and a ground to the sensor. The PCM reference voltage is necessary
because the oxygen sensors do not provide their own voltage until they reach operating temperature.
The PCM uses oxygen sensor information during "Closed Loop" operation to constantly adjust fuel control to reduce exhaust emissions. Faulty oxygen
sensors will cause various driveability conditions and should set a Diagnostic Trouble Code.
