DTC Detection Logic

WARNING: This page is about a different car, the 2019 Nissan NV3500 HD, 2019 Nissan NV2500 HD, and 2019 Nissan NV1500. 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 causes the longer switching time.

MALFUNCTION A

To judge malfunctions of heated oxygen sensor 2, ECM monitors whether the voltage is unusually high during various driving conditions such as fuel cut.

Courtesy of NISSAN NORTH AMERICA, INC.

MALFUNCTION B

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

Courtesy of NISSAN NORTH AMERICA, INC.

DTC No.

Trouble diagnosis name

(Trouble diagnosis content)

DTC detecting condition

Possible cause

P0138

HO2S2 (B1)

[Heated oxygen sensor 2 (bank 1) circuit high voltage]

An excessively high voltage from the sensor is sent to ECM.

Harness or connectors
(Heated oxygen sensor 2 circuit is open or shorted)
Heated oxygen sensor 2

The minimum voltage from the sensor is not reached to the specified voltage.

Harness or connectors
(Heated oxygen sensor 2 circuit is open or shorted)
Heated oxygen sensor 2
Fuel pressure
Fuel injector