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 voltage is unusually high during the various driving condition such as fuel-cut.

Fig 1: Heated Oxygen Sensor Signal

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

Fig 2: DTC Condition Detection Chart

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