Voyager V6-3.0L VIN 3 (2000)
Oxygen Sensor: Description and Operation
HEATED OXYGEN SENSOR (O2S SENSOR) - PCM INPUT
Fig. 6 Upstream Heated Oxygen Sensor
The upstream O2S is located in the exhaust manifold and provides an input voltage to the PCM.
Fig. 8 Downstream Heated Oxygen Sensor
The downstream heated oxygen sensor threads into the outlet pipe at the rear of the catalytic convertor.
As vehicles accumulate mileage, the catalytic convertor deteriorates. The deterioration results in a less efficient catalyst. To monitor catalytic
convertor deterioration, the fuel injection system uses two heated oxygen sensors. One sensor upstream of the catalytic convertor, one downstream
of the convertor. The PCM compares the reading from the sensors to calculate the catalytic convertor oxygen storage capacity and converter
efficiency. Also, the PCM uses the upstream heated oxygen sensor input when adjusting injector pulse width.
When the catalytic converter efficiency drops below emission standards, the PCM stores a diagnostic trouble code and illuminates the malfunction
indicator lamp (MIL).
The automatic shutdown relay supplies battery voltage to both the upstream and downstream heated oxygen sensors. The oxygen sensors are
equipped with a heating element. The heating elements reduce the time required for the sensors to reach operating temperature.
