DeVille DHS V8-4.6L VIN Y (2000)
Oxygen Sensor: Description and Operation
The heated oxygen sensors allow the PCM to maintain an air/fuel ratio that provides the best performance, fuel economy, and emission control. There
are three heated oxygen sensors mounted in the exhaust gas stream. HO2S bank 1 sensor 1 and bank 2 sensor 1 are mounted in the right and left exhaust
manifolds. HO2S bank 1 sensor 2 is mounted in the exhaust pipe after the converter. These sensors produce a voltage due to the difference in oxygen
content between the air and the exhaust gas stream. The PCM uses the fuel control heated oxygen sensors (HO2S bank 1 sensor 1 and bank 2 sensor 1) to
decide what fuel mixture command to give the fuel injectors. The PCM supplies a 450 millivolt reference voltage to the sensors. The sensors vary the
reference voltage in response to the oxygen content in the exhaust gas stream. When the oxygen content is low (a rich condition), the PCM will
detect a signal voltage near 900 millivolts. When the oxygen content is high (a lean condition), the PCM will detect a signal voltage near 100 millivolts.
The PCM adjusts the injector pulse width to correct for a rich or a lean condition. The PCM uses HO2S bank 1 sensor 2 to determine how well the
three-way catalyst is controlling emissions.
The PCM compares the signals from HO2S bank 1 sensor 1 and bank 2 sensor 1 to the signal from HO2S bank 1 sensor 2. If the catalyst is operating
efficiently, the PCM should detect a HO2S bank 1 sensor 2 signal less active than the signals from HO2S bank 1 sensor 1 and bank 2 sensor 1.
