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 of the three way catalyst (manifold) causes the longer switching time. To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the maximum voltage of the sensor is sufficiently high during the various driving condition such as fuel-cut.

Fig 1: Identifying Voltage Cycle

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

Fig 2: Diagnostic Chart

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