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Home >> Nissan-Datsun >> 2004 >> Sentra SE-R >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Qr25DE >> DTC P0139: Ho2S2 >> Component Description
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Component Description

The heated oxygen sensor 2, after three way catalyst (manifold), monitors the oxygen level in the exhaust gas.

Even if switching characteristics of the heated oxygen sensor 1 (A/T models ULEV and M/T models) or the air fuel ratio (A/F) sensor 1 (A/T models except ULEV) are shifted, the air-fuel ratio is controlled to stoichiometric, by the signal from the heated oxygen sensor 2.

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 heated oxygen sensor 2 is not used for engine control operation.

Fig 1: Identifying HO2S2
G00777065Courtesy of NISSAN MOTOR CO., U.S.A.