On Board Diagnosis Logic

The heated oxygen sensor 2 has a much longer switching time between rich and lean than the heated oxygen sensor 1. The oxygen storage capacity before the three way catalyst (manifold) causes the longer switching time. To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the minimum voltage of the sensor is sufficiently low during various driving conditions such as fuel-cut.

Fig 1: On Board Diagnosis Malfunction Graph

Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 2: DTC Detecting Condition Chart

Courtesy of NISSAN MOTOR CO., U.S.A.