On Board Diagnosis Logic

The heated oxygen sensor 2 has a much longer switching time between rich and lean than the A/F 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 switching response of the sensor's voltage is faster than specified during the various driving condition such as fuel-cut.

Fig 1: Heated Oxygen Sensor Voltage Graph

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

Fig 2: DTC Detection Condition Chart

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