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Diagnostic Procedure

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.
  1. Turn ignition off. Loosen and retighten engine ground bolts. See Figure and Figure . Loosen and retighten HO2S to 30-37 ft. lbs. (40-50 N.m). Start engine and check for exhaust leak before catalyst. Also, check for air intake leak after Mass Air Flow (MAF) sensor. Repair intake or exhaust system as necessary and retest system. If problem does not exist, go to next step.
  2. Start engine and warm engine to normal operating temperature. Turn ignition off. Disconnect 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.
  3. Ensure first trip DTC P0102 is set. Clear DTCs. Start engine and let it idle for at least 10 minutes. Recheck for DTCs. If DTC P0171 or P0172 is present and engine is hard to start, perform diagnosis for DTC P0171 or P0172. See DTC P0171 OR DTC P0172 . If DTC P0171 or P0172 is not present and engine is not hard to start, go to next step.
  4. Turn ignition off. Disconnect front HO2S harness connector. See Figure. Check continuity between ground and front HO2S harness connector terminal No. 4 (Black wire). Continuity should exist. Turn ignition on. Measure voltage between ground and front HO2S harness connector terminal No. 4 (Black wire). Voltage should be less than 0.5 volt. If circuit checks are not as specified, repair open or short circuit to voltage in Black wire between ground and front HO2S harness connector terminal No. 4. Perform DTC CONFIRMATION TEST  to verify repair. If circuit checks are as specified, go to next step.
  5. Turn ignition off. Disconnect HO2S and ECM harness connectors. Check continuity of White/Green wire between HO2S harness connector terminal No. 1 and ECM harness connector terminal No. 92. See Figure and Figure . Continuity should exist. Also, check circuit for short to ground and short to voltage. Repair circuit as necessary and perform DTC CONFIRMATION TEST . If circuit is okay, go to next step.
  6. Measure resistance between HO2S terminals. See Figure and HO2S HEATER RESISTANCE SPECIFICATIONS  for terminal selections. If HO2S tests as specified, go to next step. If HO2S does not test as specified, replace HO2S. Perform DTC CONFIRMATION TEST  to verify repair.
  7. Start engine and warm to normal operating temperature. Measure voltage between ground and ECM terminal No. 72 (Orange/Blue wire) by backprobing, with engine at specified speeds. See MASS AIRFLOW SENSOR VOLTAGE SPECIFICATIONS  under DTC P0101: MASS AIRFLOW (MAF) SENSOR. If MAF sensor operates as specified, go to next step. If MAF sensor does not operate as specified, replace sensor and perform DTC CONFIRMATION TEST  to verify repair.
  8. With engine idling, remove PCV valve with vacuum hose connected. A hissing noise should be heard from PCV valve. Strong vacuum should be felt immediately when a finger is placed over valve inlet. If operation is as specified, go to next step. If operation is not as specified, replace PCV valve and perform DTC CONFIRMATION TEST  to verify repair.
  9. Reconnect all harness connectors. Start engine and warm to normal operating temperature. Measure voltage between ground and ECM terminal No. 62 (White/Green wire) by backprobing. 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.
    CAUTION: DO NOT reuse any HO2S that has been dropped from a height of 20" (.5 m) or more onto a hard surface such as concrete.

    If operation is as specified, go to next step. If operation is not as specified, replace HO2S. Perform DTC CONFIRMATION TEST  to verify repair.

  10. No problem is indicated at this time. Problem may be intermittent. See INTERMITTENTS in TROUBLESHOOTING - NO CODES article.
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