DTC Confirmation Test (Overall Function Check)

WARNING: This page is about a different car, the 2002 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Use the following test to check overall function of rear HO2S (sensor 2) circuit. During this test, DTC may not be confirmed.

DTC P0139 will set if rear HO2S (sensor 2) response time is too long. Possible causes are:

HO2S (sensor 2) circuit open or shorted.
Defective HO2S (sensor 2).
Fuel pressure incorrect.
Defective injectors.
Intake air leaks.

Drive vehicle at a speed of more than 43 MPH for 2 consecutive minutes. Stop vehicle and leave engine running. Using a DVOM, backprobe PCM harness connector and measure voltage between ground and terminal No. 86 (White wire) at PCM harness connector. See Figure and Figure . Monitoring voltage while quickly increase engine speed to 4000 RPM and release accelerator pedal. Repeat 10 times. Voltage should change at least 0.06 volt in one second.

If voltage is not as specified, allow engine to idle for 10 minutes and recheck voltage. If voltage is still not as specified, allow vehicle to coast at 50 MPH with transmission in "D" position and overdrive off, and recheck voltage. If first trip DTC is sets, perform DIAGNOSTIC PROCEDURE . If first trip DTC is not set, problem may be intermittent. See TESTING PROCEDURE .