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Home › Nissan-Datsun › 2004 › Pathfinder SE, RWD › Repair and Diagnosis › Engine Performance › System › Engine Control System › DTC P0138, P0158: Ho2S2 › Diagnostic Procedure

Diagnostic Procedure

  1. INSPECTION START 
    1. Turn ignition switch "OFF".
    2. Loosen and retighten engine ground screws.
      Fig 1: Retightening Engine Ground Screws
      G00336429Courtesy of NISSAN MOTOR CO., U.S.A.
    3. Disconnect corresponding heated oxygen sensor 2 harness connector.
      Fig 2: Disconnecting Corresponding Heated Oxygen Sensor 2 Harness Connector
      G00336430Courtesy of NISSAN MOTOR CO., U.S.A.
    4. Disconnect ECM harness connector.
    1. GO TO 2.
  2. CHECK HO2S2 INPUT SIGNAL CIRCUIT FOR OPEN AND SHORT 
    1. Check harness continuity between ECM terminal and HO2S2 terminal as follows.

      Refer to WIRING DIAGRAM  .

      Fig 3: ECM Terminal And HO2S1 Terminals Table (For Continuity Checking)
      G00336431Courtesy of NISSAN MOTOR CO., U.S.A.

      Continuity should exist. 

    2. Check harness continuity between ECM terminal or HO2S2 terminal and ground as follows.

      Refer to  WIRING DIAGRAM   . 

      Fig 4: ECM Terminal Or HO2S2 Terminal And Ground Table (For Continuity Checking)
      G00336432Courtesy of NISSAN MOTOR CO., U.S.A.

      Continuity should not exist. 

    3. Also check harness for short to power.

    OK or NG 

    1. OK GO TO 3.
    2. NG Repair open circuit or short to ground or short to power in harness or connectors.
  3. CHECK HO2S2 GROUND CIRCUIT FOR OPEN AND SHORT 
    1. Check harness continuity between HO2S2 terminal 4 and engine ground.

      Refer to WIRING DIAGRAM  .

      Continuity should exist. 

    2. Also check harness for short to power.

    OK or NG 

    1. OK GO TO 4.
    2. NG Repair open circuit or short to power in harness or connectors.
  4. CHECK HO2S2 CONNECTORS FOR WATER 

    Check heated oxygen sensor 2 connector and harness connector for water.

    Water should not exist. 

    OK or NG 

    1. OK (With CONSULT-II) GO TO 5.
    2. OK (Without CONSULT-II) GO TO  6 .
    3. NG Repair or replace harness or connectors.
  5. CHECK HEATED OXYGEN SENSOR 2 

    With CONSULT-II 

    1. Start engine and warm it up to the normal operating temperature.
    2. Turn ignition switch "ON" and wait at least 10 seconds.
    3. Start engine and keep the engine speed between 3,500 and 4,000 RPM for at least one minute under no load.
    4. Let engine idle for one minute.
    5. Select "FUEL INJECTION" in "ACTIVE TEST" mode, and select "HO2S2 (B1)/(B2)" as the monitor item with CONSULT-II.
    6. Check "HO2S2 (B1)/(B2)" at idle speed when adjusting "FUEL INJECTION" to +/-25%.
      Fig 5: Identifying Heated Oxygen Sensor 2 Voltage Graph
      G00336433Courtesy of NISSAN MOTOR CO., U.S.A.

      "HO2S2 (B1)/(B2)" should be above 0.68V at least once when the "FUEL INJECTION" is +25%. 

      "HO2S2 (B1)/(B2)" should be below 0.48V at least once when the "FUEL INJECTION" is -25%. 

    CAUTION:
    • Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a hard surface such as a concrete floor; use a new one.
    • Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.

    OK or NG 

    1. OK GO TO  8 .
    2. NG Replace malfunctioning heated oxygen sensor 2.
  6. CHECK HEATED OXYGEN SENSOR 2-I 

    Without CONSULT-II 

    1. Start engine and warm it up to the normal operating temperature.
    2. Turn ignition switch "ON" and wait at least 10 seconds.
    3. Start engine and keep the engine speed between 3,500 and 4,000 RPM for at least one minute under no load.
    4. Let engine idle for one minute.
    5. Set voltmeter probes between ECM terminal 74 (HO2S2 bank 1 signal) or 55 (HO2S2 bank 2 signal) and engine ground.
    6. Check the voltage when revving up to 4,000 RPM under no load at least 10 times. (Depress and release accelerator pedal as soon as possible.)
      Fig 6: Checking Voltage Between ECM Terminal 74 (HO2S2 Bank 1 Signal) Or 55 (HO2S2 Bank 2 Signal) And Engine Ground
      G00336434Courtesy of NISSAN MOTOR CO., U.S.A.

      The voltage should be above 0.68V at least once during this procedure. 

    OK or NG 

    1. OK GO TO  8 .
    2. NG GO TO 7.
  7. CHECK HEATED OXYGEN SENSOR 2-II 

    Idle vehicle for 10 minutes, then check voltage between the same terminals as in Test No. 6; or check voltage when coasting from 80 km/h (50 MPH) in 3rd gear position (M/T), "D" position with "OD" OFF (A/T).

    The voltage should go below 0.48V at least once during this procedure. 

    CAUTION:
    • Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a hard surface such as a concrete floor; use a new one.
    • Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.

    OK or NG 

    1. OK GO TO 8.
    2. NG Replace malfunctioning heated oxygen sensor 2.
  8. CHECK INTERMITTENT INCIDENT 

    Refer to "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT  " .

    1. INSPECTION END 
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