Pathfinder LE 2WD V6-3.3L (VG33E) (1999)
Oxygen Sensor: Description and Operation
Front Heated Oxygen Sensor
The front heated oxygen sensor is placed into the front tube. If detects the amount of oxygen in the exhaust gas compared to the outside air. The
front heated oxygen sensor has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from approximately 1 V in richer
conditions to 0 V in leaner conditions. The front heated oxygen sensor signal is sent to the ECM. The ECM adjusts the injection pulse duration to
achieve the ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical change from 1 V to 0 V.