SFI SYSTEM, Diagnostic DTC:P0139

DTC Code DTC Name
P0139 O2 Sensor Circuit Slow Response Bank 1 Sensor 2

DESCRIPTION

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
P0139 O2 Sensor Circuit Slow Response Bank 1 Sensor 2

DTC Detection Condition


    Enable Criteria (1)

  • Engine run time 200 seconds or more

  • Mass air flow meter 10 g/sec or more

  • Pre-catalyst oxygen sensor voltage 0.6 V or higher


    Enable Criteria (2)

  • Pre-catalyst oxygen sensor voltage less than 0.322 V

  • Engine run time 200 seconds or more

  • Deceleration fuel cut off active


    Enable Criteria (3)

  • Pre-catalyst oxygen sensor voltage higher than 0.6 V threshold for a minimum of 1200 ms to allow the test to be valid. Timed from the point the post-catalyst oxygen sensor voltage increases above the 0.3 V threshold.

  • Post-catalyst oxygen sensor voltage increasing crosses 0.3 V threshold.

  • Mass air flow meter 10 g/sec or more

  • Engine run time 200 seconds or more


    Malfunction Criteria (1)

  • Post-catalyst oxygen sensor does not report rich condition 5 seconds or more


    Malfunction Criteria (2)

  • Post-catalyst oxygen sensor does not report lean condition 5 seconds or more


    Malfunction Criteria (3)-1

  • Ritch to lean sensor switch time averaged more than 700ms over 5 consecutive tests.


    Malfunction Criteria (3)-2

  • Lean to rich sensor switch time averaged more than 700ms over 5 consecutive tests.

Diagnostic Mask


  • The MIL will be illuminated if the faults are present for 2 consecutive trips

Monitor


  • -

Potential failure modes


  • -

  • Open or short in heated oxygen sensor (sensor 2) circuit

  • Heated oxygen sensor (sensor 2)

  • Fuel pressure

  • Fuel injector assembly

  • Gas leakage from exhaust system

 Comes on DTC stored

MONITOR DESCRIPTION

The oxygen sensor is electrically heated to improve response from start.

The sensor consists of zirconia electrode between two platinum plates. When zirconia comes into contact with oxygen, it becomes an electrical conductor. The exhaust gases passes through louvers in the sensor. One plate is in contact with the outside air and the other plate is in contact with the exhaust gases. The platinum plate in contact with the air is electrically negative due to the oxygen in the atmosphere and the plate in contact with the exhaust gases is electrically positive. This will cause a difference in electrical potential to develop between the two plates. Thus the voltage across the platinum plates ranges approximately from 100 millivolts to 900 millivolts, depending on the oxygen content of the exhaust gases. Thus when the air/fuel mixture is rich, the oxygen sensor output will be high. If the air/fuel mixture is lean, the oxygen sensor output will be low. The post catalyst oxygen sensor performance is a good indicator of catalyst efficiency.

WIRING DIAGRAM

Refer to DTC P0131.

Click here

CAUTION / NOTICE / HINT

Tech Tips


  • Sensor 1 refers to the sensor closest to the engine assembly.

  • Sensor 2 refers to the sensor farthest away from the engine assembly.

  • Read freeze frame data using the GTS. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE


  1. CHECK ANY OTHER DTC OUTPUT (IN ADDITION TO DTC P0139)


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine / Trouble Codes.

    5. Read the DTCs.

      Result
      Result Proceed to
      DTC P0139 is output A
      DTC P0139 and other DTCs are output B

      Tech Tips

      If any DTCs other than P0139 are output, troubleshoot those DTCs first.


    B

    GO TO DTC CHART Click here

    A

  2. READ VALUE USING GTS (O2S B1S1 AND O2S B1S2)


    1. Connect the GTS to the DLC3.

    2. Start the engine and warm it up.

    3. Turn the GTS on.

    4. Warm up the engine and run the engine at an engine speed of 2500 rpm for approximately 90 seconds.

    5. Enter the following menus: Powertrain / Engine / Data List / All Data / O2S B1S1 and O2S B1S2.

    6. Allow the engine to idle.

    7. Monitor the voltage outputs of the heated oxygen sensor (sensor 1) and heated oxygen sensor (sensor 2) (O2S B1S1 and O2S B1S2) displayed on the GTS.

      Note


      • The heated oxygen sensor (sensor 1) has an output delay of a few seconds and the heated oxygen sensor (sensor 2) has a maximum output delay of approximately 20 seconds.

      • Read the output voltage immediately after warming up the heated oxygen sensor (sensor 1) and heated heated oxygen sensor (sensor 2) to avoid an inaccurate reading due to a sensor cooling.

      Standard

      GTS Display

      (Sensor)

      		 Status Voltage

      O2S B1S1

      (Heated oxygen sensor (sensor 1))

      		 Rich Higher than 0.6 V
      Lean Below 0.322 V

      O2S B1S2

      (Heated oxygen sensor (sensor 2))

      		 Rich Higher than 0.6 V
      Lean Below 0.3 V
      Result
      Status O2S B1S1 Status O2S B1S2 Actual air fuel ratio, heated oxygen sensor (sensor 1) and heated oxygen sensor (sensor 2) condition Misfire Main Suspected Trouble Area Proceed to
      Lean/Rich Lean/Rich Normal - Heated oxygen sensor (sensor 2) A
      Lean/Rich Lean Heated oxygen sensor (sensor 2) malfunction -

      • Heated oxygen sensor (sensor 2)

      • Gas leak from exhaust system

      		 B
      Lean/Rich Rich Heated oxygen sensor (sensor 2) malfunction -

      • Heated oxygen sensor (sensor 2)

      • Gas leak from exhaust system
      Lean Lean Actual air fuel ratio lean May occur

      • Extremely lean actual air fuel ratio

      • Gas leak from exhaust system

      		 C
      Rich Rich Actual air fuel ratio rich -

      • Extremely rich actual air fuel ratio

      • Gas leak from exhaust system

      Tech Tips


      • Lean: Heated oxygen sensor (sensor 1) or Heated oxygen sensor (sensor 2) (O2S B1S1 and O2S B1S2) output voltage is consistently below 0.3 V.

      • Rich: Heated oxygen sensor (sensor 1) or Heated oxygen sensor (sensor 2) (O2S B1S1 and O2S B1S2) output voltage is consistently below 0.6 V.

      • Lean/Rich: Heated oxygen sensor alternate correctly.

      • If the vehicle is short of fuel, the air fuel ratio becomes lean and the heated oxygen sensor DTCs are recorded, and then the MIL illuminates.


    B

    CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR (SENSOR 2) - ECM) Click here

    C

    CHECK WHETHER MISFIRE OCCURS Click here

    A

  3. CHECK WHETHER DTC OUTPUT RECURS (DTC P0139)


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Clear the DTCs.

    5. Turn the engine switch off and wait for at least 30 seconds.

    6. Start the engine and warm it up.

    7. Using the GTS, confirm the vehicle conditions recorded in the freeze frame data which were present when the DTC was stored.

    8. Turn the GTS on.

    9. Enter the following menus: Powertrain / Engine / Trouble Codes.

    10. Read the DTCs.

      Result
      Result Proceed to
      DTC P0139 is output A
      DTCs are not output B

    A

    REPLACE HEATED OXYGEN SENSOR (SENSOR 2) Click here

    B

    CHECK FOR INTERMITTENT PROBLEMS Click here

  4. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR (SENSOR 2) - ECM)


    1. Disconnect the F142 heated oxygen sensor (sensor 2) connector.

    2. Disconnect the B142 ECM connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      F142-3 (OX1B) - B142-44 (OX1B) Always Below 1 Ω
      F142-1 (HT1B) - B142-46 (HT1B) Always Below 1 Ω
      F142-4 (E2) - B142-10 (EX1B) Always Below 1 Ω
      F142-3 (OX1B) or B142-44 (OX1B) - Body ground and other terminals Always 10 kΩ or higher
      F142-1 (HT1B) or B142-46 (HT1B) - Body ground and other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  5. CHECK FOR EXHAUST GAS LEAK


    1. Check for exhaust gas leaks.

      OK
      No gas leaks.
      Result
      Proceed to
      OK
      NG

    NG

    CHECK FOR EXHAUST GAS LEAK

    OK

  6. REPLACE HEATED OXYGEN SENSOR (SENSOR 2)


    1. Replace the heated oxygen sensor (sensor 2).

      Click here

      Result
      Proceed to
      NEXT

    NEXT

    END

  7. CHECK WHETHER MISFIRE OCCURS


    1. Check the idling condition.

      OK
      Rough idling does not occur.
      Result
      Proceed to
      OK
      NG

    NG

    TROUBLESHOOT MISFIRE Click here

    OK

  8. CHECK FUEL PRESSURE


    1. Check the fuel pressure.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE FUEL SYSTEM

    OK

  9. INSPECT FUEL INJECTOR ASSEMBLY (INJECTION AND VOLUME)


    1. Check the injector volume.

      Click here

      Result
      Proceed to
      OK
      NG

    OK

    CHECK FOR EXHAUST GAS LEAK

    NG

    REPLACE FUEL INJECTOR ASSEMBLY Click here