On Board Diagnosis Logic

WARNING: This page is about a different car, the 2005 Nissan 350Z. 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 before the three way catalyst 1 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: Voltage Waves Graph

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

Fig 2: DTC Detecting Condition & Possible Cause Chart

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