DTC Detection Logic

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 (manifold) causes the longer switching time.

MALFUNCTION A 

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 2 Malfunction A Voltage Signal

Courtesy of NISSAN NORTH AMERICA, INC.

MALFUNCTION B 

To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the minimum voltage of sensor is sufficiently low during the various driving condition such as fuel-cut.

Fig 2: Heated Oxygen Sensor 2 Voltage Waveform (Malfunction B)

Courtesy of NISSAN NORTH AMERICA, INC.