Diagnostic Procedure
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.
- Turn ignition off. Loosen and retighten front HO2S to 30-44 ft. lbs. (40-60 N.m). Start engine and warm to normal operating temperature. Turn ignition off. Disconnect Mass Airflow (MAF) sensor harness connector. Start engine and let it idle for at least 5 seconds. Turn ignition off and reconnect MAF sensor harness connector. Go to next step.
- Ensure first trip DTC P0100 is set. Clear DTCs. Start engine and let it idle for at least 10 minutes. Recheck for DTCs. If DTC P0172 is present and engine is hard to start, perform diagnosis for DTC P0172. SeeDTC P0171 OR DTC P0172: FUEL INJECTION SYSTEM FUNCTION . If DTC P0172 is not present and engine is not hard to start, go to next step.
- Turn ignition off. Disconnect front HO2S harness connector located near oil filler cap. Check harness connector for water and/or damage. Repair connector as necessary and retest system. If connector is okay, go to next step.
- Measure resistance between front HO2S connector terminals No. 1 and 3 (component side). Resistance should be 2.3-4.3 ohms at 77°F (25°C). Check continuity between front HO2S connector terminals No. 1 and 2, and between terminals No. 2 and 3 (component side). Continuity should not exist. If resistance and continuity are as specified, go to next step. If resistance or continuity is not as specified, replace front HO2S and retest system.
- Reconnect all harness connectors. Start engine and warm to normal operating temperature. Measure voltage between ground and ECM terminal No. 50 (Light Green wire) by backprobing. See Figure and Figure
. Increase engine speed to 2000 RPM. The following conditions should exist:
- Voltage cycles from 0-0.3 volt to 0.6-1.0 volt and back more than 5 times within 10 seconds.
- Maximum voltage is more than .6 volt at least once.
- Minimum voltage is less than .3 volt at least once.
- Voltage never exceeds one volt.
If operation is as specified, go to next step. If operation is not as specified, replace front HO2S and retest system.
- Turn ignition off. Disconnect 42-pin super multiple junction connector F-12 from firewall. Check continuity between ground and engine control harness connector terminal No. 8A (Black/Red wire). See Figure. Continuity should exist. Also, check circuit for short to voltage. Repair circuit as necessary and retest system. If circuit is okay, go to next step.
- No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article.
CAUTION:
DO NOT use ECM ground terminals when measuring voltage.