On Board Diagnosis Logic

WARNING: This page is about a different car, the 2004 Nissan Murano. However, it is still accessible from the selected car via links, so may be relevant.

The heated oxygen sensor 2 has a much longer switching time between rich and lean than the air fuel ratio (A/F) sensor 1. The oxygen storage capacity of the three way catalyst 1 (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: Identifying Proper Voltage Flow

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

Fig 2: On Board Diagnosis Logic Chart (P0138, P0158)

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