Theory Of Operation

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This vehicle is equipped with a 5-wire wide-band O2 Sensor. This sensor operates differently from traditional O2 Sensors. The wide-band O2 Sensor tip consists of two cells that provide different functions, a measurement chamber and a detection chamber with pumping capabilities. The oxygen pumping function is the ability to pump oxygen into or out of the measurement chamber depending on the level of oxygen in the measurement chamber. This function provides the wide-band sensing capabilities and is critical for proper oxygen measurement.

The Powertrain Control Module (PCM) monitors the exhaust gases for oxygen content and varies the rich/lean fuel mixture of the intake air fuel mixture to adjust the system. The monitor evaluates response time of the O2 Sensor during transition from load to overrun mode using the O2 concentration (corrected for exhaust pressure) signal. The PCM will illuminate the MIL lamp when the diagnostic runs and fails.