DTC Detection Logic

WARNING: This page is about a different car, the 2011 Infiniti QX56. 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 (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 various driving conditions such as fuel cut.

Fig 1: Heated Oxygen Sensor 2 Voltage Signal Pattern

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

DTC DETECTION LOGIC

DTC No.	Trouble diagnosis name (Trouble diagnosis content)	DTC detecting condition	Possible cause
P0139	HO2S2 (B1) [Heated oxygen sensor 2 (bank 1) circuit slow response]	It takes more time for the sensor to respond between rich and lean than the specified time.	Harness or connectors (The heated oxygen sensor 2 circuit is open or shorted) Heated oxygen sensor 2 Fuel pressure Fuel injector Intake air leaks
P0159	HO2S2 (B2) [Heated oxygen sensor 2 (bank 2) circuit slow response]