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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 41 (Engine Controls - Self-Diagnostics - Quest) >> Diagnostic Tests >> DTC P0133: Front Heated Oxygen Sensor >> Diagnostic Procedure

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.
  1. Turn ignition off. Loosen and retighten engine ground bolts. See Figure. Loosen and retighten front HO2S to 30-44 ft. lbs. (40-60 N.m). Start engine and check for exhaust leak before catalyst. Also, check for air intake leak after 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 P0100 is set. Clear DTCs. Start engine and let it idle for at least 10 minutes. Recheck for DTCs. If DTC P0171 or DTC P0172 is present and engine is hard to start, perform diagnosis for DTC P0171 or DTC P0172. See DTC P0171 OR DTC P0172: FUEL INJECTION SYSTEM FUNCTION . If DTC P0171 or DTC P0172 is not present and engine is not hard to start, go to next step.
  4. Turn ignition off. Disconnect front HO2S harness connector located near oil filler cap. Disconnect ECM harness connector. See Figure. Check continuity of Light Green wire between front HO2S harness connector terminal No. 2 and ECM harness connector terminal No. 50. See Figure. Continuity should exist. Also, check circuit for short to ground and short to voltage. Repair circuit as necessary and retest system. If circuit is okay, go to next step.
  5. Measure resistance between 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 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 HO2S and retest system.
    6. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  6. Start engine and warm to normal operating temperature. Measure voltage between ground and ECM terminal No. 54 (White/Blue wire) by backprobing, with engine at specified speeds. See MASS AIRFLOW SENSOR VOLTAGE  table under DTC P0100: MASS AIRFLOW (MAF) SENSOR. Go to next step.
  7. If voltage is as specified, go to next step. If voltage is not as specified, disconnect and reconnect MAF sensor harness connector and repeat step  6. If voltage is still not as specified, replace MAF sensor and retest system. If voltage is now as specified, go to next step.
  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 retest system.
    9. CAUTION: DO NOT use ECM ground terminals when measuring voltage.
  9. 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. 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.

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