Pathfinder 4WD V6-3.3L (VG33E) (1996)
2. Set voltmeter probes between ECM terminal (46) (sensor signal) and (43) (engine ground).
3. Check the following with engine speed held at 2,000 rpm constant under no load.
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Malfunction indicator lamp goes on more than 5 times within 10 seconds in Diagnostic Test Mode (FRONT HEATED OXYGEN SENSOR
MONITOR).
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The maximum voltage is over O.6V at least one time.
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The minimum voltage is below O.35V at least one time.
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the voltage never exceeds 1.0V.
COMPONENT INSPECTION
Check resistance between terminals (3) and (1).
Resistance: 2.3 - 4.3 ohms at 25°C (77°F)
Check continuity between terminals (2) and (1), (3) and (2).
Continuity should not exist.
If NG, replace the front 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 0707 Rear Heated Oxygen Sensor
Rear Heated Oxygen Sensor
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.