Pathfinder 4WD V6-3.3L (VG33E) (1996)
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Continuity
2. Check continuity.
If NG, replace the rear heated oxygen sensor.
CAUTION: Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a hard surface such as a
concrete floor; use a new one.
DTC 0708 Rear Heated Oxygen Sensor (LB)
DESCRIPTION
The rear heated oxygen sensor (Rear HO2S), after three way catalyst, monitors the oxygen level in the exhaust gas. Even if switching characteristics of
the front heated oxygen sensor are shifted, the air fuel ratio is controlled to stoichiometric, by the signal from the rear heated oxygen sensor.
This sensor is made of ceramic zirconia. The zirconia generates voltage from approximately 1V in richer conditions to 0V in leaner conditions. Under
normal conditions the rear heated oxygen sensor is not used for engine control operation.
ON BOARD DIAGNOSIS LOGIC
The rear heated oxygen sensor has a much longer switching time between rich and lean than the front heated oxygen sensor. The oxygen storage
capacity before the three way catalyst causes the longer switching time. To judge the malfunctions of rear heated oxygen sensor, ECM monitors the
sensor's voltage value and the switching response during the various driving condition such as fuel-cut.
