DTC Confirmation Test (Overall Function Check)

WARNING: This page is about a different car, the 2002 Nissan Quest. 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 front HO2S circuit. During this test, DTC may not be confirmed.

Malfunction is detected when HO2S response time is too long. Possible causes are:

HO2S circuit open or shorted.
Defective HO2S.
Defective HO2S heater.
Fuel pressure incorrect.
Defective injectors.
Intake air leaks.
Exhaust leaks.
PCV system malfunction.
Defective Mass Airflow (MAF) sensor.

CAUTION: DO NOT use ECM ground terminals when measuring voltage.

To check front HO2S circuit, start engine and warm to normal operating temperature. Measure voltage ground and ECM terminal No. 50 (Light Green wire) by backprobing. See Figure and Figure . Monitor voltage while holding engine speed at 2000 RPM. Voltage should fluctuate from 0-.3 volt to .6-1.0 volt and back more than 5 times within 10 seconds. If voltage is not as specified, perform DIAGNOSTIC PROCEDURE .