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 switching response of the sensor's voltage is faster than specified during the various driving condition such as fuel-cut.

Fig 1: Identifying Heated Oxygen Sensor 2 Voltage Signal

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

Fig 2: DTC P0139 And P0159 Diagnostic Chart

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