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Home >> Nissan-Datsun >> 2003 >> Sentra Limited >> Repair and Diagnosis >> External Pages >> Different car >> Section 39 (Engine Controls - Self-Diagnostics - 1.8L - XE, GXE) >> Diagnostic Tests >> DTC P0138 Or DTC P0158 >> Diagnostic Procedure

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.
NOTE: For circuit wiring diagram, see Fig 1 or Fig 2 . For connector identification and locations, see CONNECTOR IDENTIFICATION  .

  1. Retighten Ground Screws

    Turn ignition off. Loosen and retighten engine ground screws. See Figure . Go to next step.

  2. Check Input Signal Circuit

    Disconnect appropriate HO2S2 harness connector. See Figure . Disconnect ECM harness connector. See Figure . Check continuity between HO2S2 harness connector terminal No. 1 and ECM harness connector terminal No. 95 (bank 1) or No. 63 (bank 2). See Fig 1 or Fig 2 . Continuity should exist. Also, check harness for short to ground and short to power. If problem is found, repair as necessary. Perform DTC CONFIRMATION TEST  to verify repair. If problem is not found, go to next step.

  3. Check Ground Circuit

    Check continuity between engine ground and HO2S2 harness connector terminal No. 4. Continuity should exist. Also, check harness for short to power. If problem is found, repair as necessary. Perform DTC CONFIRMATION TEST  to verify repair. If problem is not found, go to next step.

  4. Check Harness Connector

    Check HO2S2 harness connector for water. If water exists, repair or replace connector as necessary. Perform DTC CONFIRMATION TEST  to verify repair. If water does not exist, go to next step.

  5. Check HO2S2

    Start engine and warm to normal operating temperature. Stop vehicle with engine running.

    With CONSULT-II

    1. Select FUEL INJECTION in ACTIVE TEST mode. Select HO2S2 (B1) (B2) as the monitor item. Adjust FUEL INJECTION to +25%. HO2S2 (B1) (B2) voltage should be more than .48 volt at least once. Adjust FUEL INJECTION to -25%. HO2S2 (B1) (B2) voltage should be less than .43 volt at least once. If operation is as specified, go to next step. If operation is not as specified, replace HO2S2. Perform DTC CONFIRMATION TEST  to verify repair.

    Without CONSULT-II

    1. Measure voltage between engine ground and ECM terminal No. 95 (bank 1) or No. 63 (bank 2) by backprobing. While monitoring voltage, snap throttle to 4000 RPM at least 10 times. Voltage should be more than .48 volt at least once. If voltage is as specified, go to next step. If voltage is not as specified, try the following:
      • Snap throttle to 6000 RPM and recheck voltage.
      • Let engine idle for 10 minutes and recheck voltage.
      • Check voltage while coasting from 50 MPH in 3rd gear.

      Voltage should be less than .43 volt at least once. If voltage is not as specified, replace HO2S2. Perform DTC CONFIRMATION TEST  to verify repair.

  6. Check For Intermittent

    Check for intermittent condition. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. Perform DTC CONFIRMATION TEST  to verify repair.
Fig 1: HO2S2 Wiring Diagram (Bank 1)
G00164605Courtesy of NISSAN MOTOR CO., U.S.A.
Fig 2: HO2S2 Wiring Diagram (Bank 2)
G00164606Courtesy of NISSAN MOTOR CO., U.S.A.
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