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, first trip DTC may not be confirmed.
Malfunction is detected when ECM receives a constant .3 volt from front HO2S. When ECM is not using front HO2S signal as an input, ECM circuits read a continuous .3 volt. Therefore, ECM monitors the time that front HO2S voltage is .2-.4 volt. DTC will set if time is too long. Possible causes are:
- HO2S circuit open or shorted.
- Defective HO2S.
CAUTION:
DO NOT use ECM ground terminals when measuring voltage.
To check front HO2S circuit, measure voltage between ground and ECM terminal No. 50 (Light Green wire) by backprobing. See Figure and Figure . Start engine and warm to normal operating temperature. Monitor voltage while holding engine speed at 2000 RPM. Voltage should not remain in the .2-.4 volt range. If voltage is not as specified, go to DIAGNOSTIC PROCEDURE .