2001 Infiniti I30 V6-2988cc 3.0L DOHC Heated Oxygen Sensor

The heated oxygen sensor 2 (rear), after three way catalyst (Manifold), monitors the oxygen
level in the exhaust gas on each bank.
Even if switching characteristics of the heated oxygen sensor 1 (front) are shifted, the air
fuel ratio is controlled to stoichiometric, by the signal from the heated oxygen sensor 2
(rear).
This sensor is made of ceramic zirconia. The zirconia generates voltage from
approximately 1 V in richer conditions to 0 V in leaner conditions.
Under normal conditions the heated oxygen sensor 2 (rear) is not used for engine control
operation.
On Board Diagnosis Logic
The heated oxygen sensor 2 (rear) has a much longer switching time between rich and lean
than the heated oxygen sensor 1 (front). The oxygen storage capacity before the three
way catalyst (Manifold) causes the longer switching time. To judge the malfunctions of
heated oxygen sensor 2 (rear), ECM monitors whether the maximum voltage of the
sensor is sufficiently high during the various driving condition such as fuel-cut.
Malfunction is detected when the maximum voltage from the sensor is not reached to the
specified voltage.

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