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Nissan Sentra B18 (2020-2025) Service Manual: P0139 Ho2s2

Dtc Description

DTC Description

The heated oxygen sensor 2 has a much longer switching time between rich and lean than the air fuel ratio (A/F) sensor 1. The oxygen storage capacity of the three way catalyst 1 causes the longer switching time. To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the switching response of the sensor's voltage is faster than specified during various driving conditions such as fuel cut.

DTC DETECTION LOGIC

DTC

CONSULT screen terms

(Trouble diagnosis content)

DTC detection condition

P0139

HO2S2 (B1)

(O2 sensor circuit slow response bank 1 sensor 2)

Diagnosis condition

—

Signal (terminal)

Heated oxygen sensor 2 signal

Threshold

The switching time between rich and lean of a heated oxygen sensor 2 signal delays more than the specified time computed by ECM

Diagnosis delay time

—

POSSIBLE CAUSE

  • Harness or connectors (The sensor circuit is open or shorted.)

  • Heated oxygen sensor 2

  • Fuel system

  • EVAP system

  • Intake air system

FAIL-SAFE

Not applicable

Confirmation Procedure

Confirmation Procedure

  1. CHECK DTC PRIORITY

    If DTC P0139 is displayed with DTC P0137 and P0138, first perform the trouble diagnosis for DTC P0137 and P0138.

    Is applicable DTC detected?

    YES >>

    Perform diagnosis of applicable.

    • DTC P0137: Refer to DTC Description.

    • DTC P0138: Refer to DTC Description.

    NO >>

    GO TO 2.

  2. INSPECTION START

    Do you have CONSULT?

    YES >>

    GO TO 3.

    NO >>

    GO TO 8.

  3. PRECONDITIONING

    If DTC Confirmation Procedure has been previously conducted, always perform the following procedure before conducting the next test.

    1. Turn ignition switch OFF and wait at least 10 seconds.

    2. Turn ignition switch ON.

    3. Turn ignition switch OFF and wait at least 10 seconds.

    TESTING CONDITION:

    For better results, perform “DTC WORK SUPPORT” at a temperature of 0 to 30°C (32 to 86°F).

    >>

    GO TO 4.

  4. PERFORM DTC CONFIRMATION PROCEDURE

    With CONSULT

    1. Turn ignition switch ON and select “DATA MONITOR” mode of “ENGINE” using CONSULT.

    2. Start engine and warm it up to the normal operating temperature.

    3. Turn ignition switch OFF and wait at least 10 seconds.

    4. Turn ignition switch ON.

    5. Turn ignition switch OFF and wait at least 10 seconds.

    6. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.

    7. Let engine idle for 1 minute.

    8. Make sure that “COOLANT TEMP/S” indicates more than 70°C (158°F).

    9. Drive the Nissan Sentra vehicle in a proper at 60 km/h (38 MPH) and maintain the speed.

      CAUTION:

      Always drive vehicle at a safe speed.

    10. Release the accelerator pedal fully at least 5 seconds.

      CAUTION:

      • Enable engine brake.

      • Always drive carefully.

      • Never apply brake when releasing the accelerator pedal.

    11. Repeat step 9 and 10 at least 8 times.

    12. Check the following item of “DATA MONITOR”.

      Data monitor item

      Status

      HO2 S2 DIAG1 (B1)

      CMPLT

      HO2 S2 DIAG2 (B1)

    Is “CMPLT” displayed on CONSULT screen?

    YES >>

    GO TO 7.

    NO-1: “CMPLT” is not displayed on DIAG 1 >>

    Perform DTC confirmation procedure again.

    NO-2: “CMPLT” is not displayed on DIAG 2 >>

    GO TO 5.

  5. PERFORM DTC WORK SUPPORT

    1. Open engine hood.

    2. Select “HO2S2 (B1) P0139” in “DTC WORK SUPPORT” mode of “ENGINE” using CONSULT.

    3. Start engine and follow the instruction of CONSULT display.

      Note:

      It will take at most 10 minutes until “COMPLETED” is displayed.

    Is “COMPLETED” displayed on CONSULT screen?

    YES >>

    GO TO 7.

    NO >>

    GO TO 6.

  6. PERFORM DTC CONFIRMATION PROCEDURE AGAIN

    1. Turn ignition switch OFF and leave the Nissan Sentra vehicle in a cool place (soak the vehicle).

    2. Perform DTC confirmation procedure again.

    >>

    GO TO 4.

  7. PERFORM SELF-DIAGNOSIS

    With CONSULT

    Perform ECM self-diagnosis.

    Is DTC “P0139” detected?

    YES >>

    Proceed to DTC Diagnosis Procedure.

    NO-1 >>

    To check malfunction symptom before repair: Refer to Intermittent Incident.

    NO-2 >>

    Confirmation after repair: INSPECTION END

  8. PERFORM COMPONENT FUNCTION CHECK-1

    Without CONSULT

    1. Start engine and warm it up to normal operating temperature.

    2. Turn ignition switch OFF and wait at least 10 seconds.

    3. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.

    4. Let engine idle for 1 minute.

    5. Check the voltage between ECM harness connector and ground as per the following condition.

      ECM

      Condition

      Voltage

      Connector

      +

      −

      Terminal

      F25

      77

      76

      Revving up to 4,000 rpm under no load at least 10 times.

      A change of voltage should be more than 0.96 V for 1 second during this procedure.

    Is the inspection result normal?

    YES-1 >>

    To check malfunction symptom before repair: Refer to Intermittent Incident.

    YES-2 >>

    Confirmation after repair: INSPECTION END

    NO >>

    GO TO 9.

  9. PERFORM COMPONENT FUNCTION CHECK-2

    Without CONSULT

    Check the voltage between ECM harness connector and ground as per the following condition.

    ECM

    Condition

    Voltage

    Connector

    +

    −

    Terminal

    F25

    77

    76

    Keeping engine speed at idle for 10 minutes.

    A change of voltage should be more than 0.96 V for 1 second during this procedure.

    Is the inspection result normal?

    YES-1 >>

    To check malfunction symptom before repair: Refer to Intermittent Incident.

    YES-2 >>

    Confirmation after repair: INSPECTION END

    NO >>

    GO TO 10.

  10. PERFORM COMPONENT FUNCTION CHECK-3

    Without CONSULT

    Check the voltage between ECM harness connector and ground as per the following condition.

    ECM

    Condition

    Voltage

    Connector

    +

    −

    Terminal

    F25

    77

    76

    Coasting from 80 km/h (50 MPH) in D position (CVT) or 4th position (M/T).

    A change of voltage should be more than 0.96 V for 1 second during this procedure.

    Is the inspection result normal?

    YES-1 >>

    To check malfunction symptom before repair: Refer to Intermittent Incident.

    YES-2 >>

    Confirmation after repair: INSPECTION END

    NO >>

    Refer to DTC Diagnosis Procedure.

Dtc Diagnosis Procedure

DTC Diagnosis Procedure

  1. CHECK DTC PRIORITY

    If DTC P0139 is displayed with DTC P0137 and P0138, first perform the trouble diagnosis for DTC P0137 and P0138.

    Is applicable DTC detected?

    YES >>

    Perform diagnosis of applicable.

    • DTC P0137: Refer to DTC Description.

    • DTC P0138: Refer to DTC Description.

    NO >>

    GO TO 2.

  2. CLEAR THE MIXTURE RATIO SELF-LEARNING VALUE

    1. Clear the mixture ratio self-learning value. Refer to Work Procedure.

    2. Run engine for at least 10 minutes at idle speed.

    Is the 1st trip DTC P0171 or P0172 detected? Is it difficult to start engine?

    YES >>

    Perform trouble diagnosis for DTC P0171 or P0172. Refer to DTC Description. or Refer to DTC Description.

    NO >>

    GO TO 3.

  3. CHECK HO2S2 GROUND CIRCUIT

    1. Turn ignition switch OFF.

    2. Disconnect heated oxygen sensor 2 harness connector.

    3. Disconnect ECM harness connector.

    4. Check the continuity between HO2S2 harness connector and ECM harness connector.

      HO2S2

      ECM

      Continuity

      Connector

      Terminal

      Connector

      Terminal

      E72

      1

      F25

      76

      Existed

    5. Also check harness for short to power.

    Is the inspection result normal?

    YES >>

    GO TO 4.

    NO >>

    Repair or replace error-detected parts.

  4. CHECK HO2S2 INPUT SIGNAL CIRCUIT

    1. Check the continuity between HO2S2 harness connector and ECM harness connector.

      HO2S2

      ECM

      Continuity

      Connector

      Terminal

      Connector

      Terminal

      E72

      2

      F25

      77

      Existed

    2. Check the continuity between HO2S2 harness connector and ground, or ECM harness connector and ground.

      HO2S2

      —

      Continuity

      Connector

      Terminal

      E72

      2

      Ground

      Not existed

      ECM

      —

      Continuity

      Connector

      Terminal

      F25

      77

      Ground

      Not existed

    3. Also check harness for short to power.

    Is the inspection result normal?

    YES >>

    GO TO 5.

    NO >>

    Repair or replace error-detected parts.

  5. CHECK HEATED OXYGEN SENSOR 2

    Check the heated oxygen sensor 2. Refer to Component Inspection.

    Is the inspection result normal?

    YES >>

    INSPECTION END

    NO >>

    GO TO 6.

  6. REPLACE HEATED OXYGEN SENSOR 2

    Replace heated oxygen sensor 2. Refer to Exploded View.

    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.

    >>

    INSPECTION END

    P0137 Ho2s2
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