SFI SYSTEM (w/ Electronic Throttle Control System), Diagnostic DTC:P0139

DTC Code DTC Name
P0139 Oxygen Sensor Circuit Slow Response (Bank 1 Sensor 2)

DESCRIPTION

In order to obtain a high purification rate for the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a Three-Way Catalytic Converter (TWC) is used. For the most efficient use of the TWC, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric air-fuel ratio. The heated oxygen sensor has the characteristic whereby its output voltage changes suddenly in the vicinity of the stoichiometric air-fuel ratio. This is used to detect the oxygen concentration in the exhaust gas and provide the ECM with feedback to control the air-fuel ratio. When the air-fuel ratio becomes lean, the oxygen concentration in the exhaust gas increases. The heated oxygen sensor informs the ECM of the lean condition (low voltage, i.e. less than 0.45 V). When the air-fuel ratio is richer than the stoichiometric air-fuel level, the oxygen concentration in the exhaust gas is reduced. And the heated oxygen sensor informs the ECM of the rich condition (high voltage, i.e. more than 0.45 V). The ECM judges by the voltage output of the heated oxygen sensor whether the air-fuel ratio is rich or lean and controls the injection time accordingly. If a malfunction of the heated oxygen sensor causes an output of abnormal voltage, the ECM is unable to perform accurate air-fuel ratio control. The heated oxygen sensor includes a heater which heats the zirconia element. The heater is controlled by the ECM. When the intake air volume is low (the temperature of the exhaust gas is low), a current flows to the heater in order to heat the sensor for accurate oxygen concentration detection.

A0137QPE01
DTC No. DTC Detection Condition Trouble Area
P0139 While driving for 10 minutes or more at vehicle speed of 70 to 110 km/h (44 to 68 mph) with transmission in 5th, heated oxygen sensor (sensor 2) signal does not switch from rich to lean or vice versa for 50 seconds (3 trip detection logic).

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

  • Heated oxygen sensor (sensor 2)

  • Fuel pressure

  • Injector

  • Gas leakage from exhaust system

  • ECM

WIRING DIAGRAM

A0136ZHE01

CONFIRMATION DRIVING PATTERN

DTC P0139 is detected when the vehicle is driven for 10 minutes or more at a vehicle speed between 70 km/h (43 mph) and 100 km/h (62 mph) with the transmission gear selector leave in the 5th position.

INSPECTION PROCEDURE

Tech Tips

Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. 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 OTHER DTC OUTPUT


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON and turn the intelligent tester ON.

    3. Select the following menu items: Powertrain / Engine and ECT / DTC.

    4. Read the DTCs.

      Result
      Display (DTC Output) Proceed To
      P0139 A
      P0139 and other DTCs B

      Tech Tips

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


    B

    GO TO DTC CHART

    A

  2. PERFORM ACTIVE TEST BY INTELLIGENT TESTER (Control the Injection Volume for A/F Sensor)


    1. Connect the intelligent tester to the DLC3.

    2. Start the engine and turn the intelligent tester ON.

    3. Warm up the engine.

    4. Run the engine at 2,500 rpm for approximately 3 minutes.

    5. On the intelligent tester, select the following menu items: Powertrain / Engine and ECT / Active Test / A/F Control.

    6. Perform the A/F control operation with the engine in an idle condition (press the right or left button to charge the fuel injection volume).

    7. Monitor the voltage output of the heated oxygen sensors (O2S B1S1 and O2S B1S2) displayed on the tester.

      Result
      The heated oxygen sensor reacts in accordance with increases and decreases of the fuel injection volume:
      +25 % = Rich output
      More than 0.5 V
      -12.5 % = Lean output
      Less than 0.4 V

      Note


      • Sensor 1 (front sensor) has an output delay of a few seconds.

      • Sensor 2 (rear sensor) has maximum output delay of approximately 20 seconds.

      Output voltage of heated oxygen sensor (sensor 1: front sensor) Output voltage of heated oxygen sensor (sensor 2: rear sensor) Mainly suspected trouble area
      Case 1

      Injection Volume

      +25 %

      -12.5 %

      		 A013833

      Injection Volume

      +25 %

      -12.5 %

      		 A013833 -

      Output voltage

      More than 0.5 V

      Less than 0.4 V

      		 A0138I9

      Output voltage

      More than 0.5 V

      Less than 0.4 V

      		 A0137EA
      Case 2

      Injection Volume

      +25 %

      -12.5 %

      		 A013833

      Injection Volume

      +25 %

      -12.5 %

      		 A013833

      • Heated oxygen sensor (Sensor 2)

      Output voltage

      Almost no reaction

      		 A0138I9

      Output voltage

      More than 0.5 V

      Less than 0.4 V

      		 A0136RO
      Case 3

      Injection Volume

      +25 %

      -12.5 %

      		 A013833

      Injection Volume

      +25 %

      -12.5 %

      		 A013833

      • Extremely rich or lean actual air-fuel ratio

      • Injector leakage or blockage

      • Gas leakage from exhaust system

      • Ignition system

      • Fuel pressure

      • Manifold absolute pressure sensor

      • Engine coolant temperature sensor

      Output voltage

      Almost no reaction

      		 A0136RO

      Output voltage

      Almost no reaction

      		 A0136RO

      The following procedure enables the technician to check and graph the voltage output of both the heated oxygen sensors.

      To display the graph, select the following menu items on the tester: View / Line Graph.

      Tech Tips

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

      Result
      Result Proceed To
      Case 1 C
      Case 2 A
      Case 3 B

    B

    CHECK WHETHER MISFIRE OCCURS Click here

    C

    PERFORM CONFIRMATION DRIVING PATTERN Click here

    A

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


    1. A01368PE01

      Disconnect the B23 heated oxygen sensor connector.

    2. Disconnect the B26 ECM connector.

    3. Measure the resistance.

      Standard resistance (Check for open)
      Tester Connection Specified Condition
      OX (B23-3) - OX1B (B26-17) Below 1 Ω
      E1 (B23-4) - E12 (B26-11) Below 1 Ω
      Standard resistance (Check for short)
      Tester Connection Specified Condition
      OX (B23-3) or OX1B (B26-17) - Body ground 10 kΩ or higher

    4. Reconnect the heated oxygen sensor connector.

    5. Reconnect the ECM connector.

      A0138NYE11

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

  4. REPLACE HEATED OXYGEN SENSOR (SENSOR 2)


    NEXT

  5. CHECK IF DTC OUTPUT RECURS


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON and turn the intelligent tester ON.

    3. Select the following menu items: Powertrain / Engine and ECT / DTC / Pending.

    4. Read DTCs.

      Result
      Display (DTC Output) Proceed To
      No output A
      P0139 B

    B

    CHECK WHETHER MISFIRE OCCURS Click here

    A

    END

  6. CHECK WHETHER MISFIRE OCCURS


    1. Check the idling condition.

      OK
      Rough idle does not occur.

    NG

    REPAIR TROUBLESHOOT MISFIRE

    OK

  7. CHECK FUEL PRESSURE


    1. Check the fuel pressure Click here.

      Standard
      304 to 343 kPa (3.1 to 3.5 kgf/cm2, 44.1 to 49.7 psi)

    NG

    REPAIR OR REPLACE AIR INDUCTION SYSTEM

    OK

  8. INSPECT FUEL INJECTOR


    1. Check the injection volume Click here.

      Standard
      47 to 58 mm3 (2.87 to 3.54 cu in.) in 15 seconds

    NG

    REPLACE FUEL INJECTOR

    OK

    CHECK FOR EXHAUST GAS LEAKS

  9. PERFORM CONFIRMATION DRIVING PATTERN


    NEXT

  10. CHECK IF DTC OUTPUT RECURS


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON and turn the intelligent tester ON.

    3. Select the following menu items: Powertrain / Engine and ECT / DTC / Pending.

    4. Read DTCs.

      Result
      Display (DTC Output) Proceed To
      No output A
      P0139 B

    B

    GO TO "CHECK FOR INTERMITTENT PROBLEMS"

    A

    REPLACE HEATED OXYGEN SENSOR (SENSOR 2)