СИСТЕМА SFI, Diagnostic DTC:P0136, P0137, P0138

DTC Code DTC Name
P0136 Oxygen Sensor Circuit (Bank 1 Sensor 2)
P0137 Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2)
P0138 Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2)

DESCRIPTION

In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbon (HC) and nitrogen oxide (NOx) components in the exhaust gas, a TWC (Three-Way Catalytic Converter) 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 level. For the purpose of helping the ECM to deliver accurate air fuel ratio control, a heated oxygen sensor is used.

The heated oxygen sensor is located behind the TWC, and detects the oxygen concentration in the exhaust gas. Since the sensor is integrated with the heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (the exhaust gas temperature is low).

When the air fuel ratio becomes lean, the oxygen concentration in the exhaust gas is high. The heated oxygen sensor informs the ECM that the post-TWC air fuel ratio is lean (low voltage, i.e. less than 0.45 V).

Conversely, when the air fuel ratio is richer than the stoichiometric air fuel level, the oxygen concentration in the exhaust gas is low. The heated oxygen sensor informs the ECM that the post-TWC air fuel ratio is rich (high voltage, i.e. higher than 0.45 V). The heated oxygen sensor has the property of changing its output voltage drastically when the air fuel ratio is close to the stoichiometric level.

The ECM uses the supplementary information from the heated oxygen sensor to determine whether the air fuel ratio after the TWC is rich or lean, and adjusts the fuel injection duration accordingly. Thus, if the heated oxygen sensor is working improperly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air fuel ratio control.

B006LNXE03
DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory
P0136 Oxygen Sensor Circuit (Bank 1 Sensor 2)

Abnormal voltage output:

During active air fuel ratio control, the following conditions (a) and (b) are met for a certain period of time (2 trip detection logic)


  • (a) Heated oxygen sensor voltage does not decrease to less than 0.21 V.

  • (b) Heated oxygen sensor voltage does not increase to 0.69 V or higher.


  • Heated oxygen sensor (sensor 2) circuit

  • Heated oxygen sensor (sensor 2)

  • Air fuel ratio sensor (sensor 1)

  • Gas leak from exhaust system

  • Fuel pressure

  • Fuel system

  • PCV valve and hose

  • Intake system

Comes on (Euro-OBD) / - (Except Euro-OBD) DTC stored (Euro-OBD) / - (Except Euro-OBD)
P0137 Oxygen Sensor Circuit Low Voltage (Bank 1 Sensor 2)

Low voltage (open):

During active air fuel ratio control, the following conditions (a) and (b) are met for a certain period of time (2 trip detection logic)


  • (a) Heated oxygen sensor voltage output is less than 0.21 V.

  • (b) Target air fuel ratio rich.


  • Heated oxygen sensor (sensor 2) circuit

  • Heated oxygen sensor (sensor 2)

  • Air fuel ratio sensor (sensor 1)

  • Gas leak from exhaust system

Comes on DTC stored
P0138 Oxygen Sensor Circuit High Voltage (Bank 1 Sensor 2)

High voltage (short):

During active air fuel ratio control, the following conditions (a) and (b) are met for a certain period of time (2 trip detection logic)


  • (a) Heated oxygen sensor voltage output is higher than 0.69 V.

  • (b) Target air fuel ratio lean.


  • Heated oxygen sensor (sensor 2) circuit

  • Heated oxygen sensor (sensor 2)

  • Air fuel ratio sensor (sensor 1)

  • ECM

Comes on (Euro-OBD) / - (Except Euro-OBD) DTC stored (Euro-OBD) / - (Except Euro-OBD)

MONITOR DESCRIPTION




MONITOR STRATEGY

Required Sensors/Components (Main) Heated oxygen sensor (sensor 2)
Required Sensors/Components (Related)

Crankshaft position sensor

Engine coolant temperature sensor

Mass air flow meter sub-assembly

Throttle position sensor

Air fuel ratio sensor

Frequency of Operation Once per driving cycle

TYPICAL ENABLING CONDITIONS

Heated Oxygen Sensor Voltage Check (Voltage Malfunction, High Voltage and Low Voltage)
Active air fuel ratio control Executing
Active air fuel ratio control begins when all of the following conditions met: -
Battery voltage 11 V or higher
Engine coolant temperature 75°C (167°F) or higher
Idling Off
Engine speed Less than 4000 rpm
Air fuel ratio sensor status Activated
Fuel system status Closed loop
Engine load 10% or higher, and less than 90%

TYPICAL MALFUNCTION THRESHOLDS

P0136: Heated Oxygen Sensor Voltage Check (Voltage Malfunction)
Either of the following conditions is met 1 or 2
1. Both of the following conditions are met -
(a) Commanded air fuel ratio 14.4 or less
(b) Heated oxygen sensor voltage 0.21 V or higher, and less than 0.69 V
2. Both of the following conditions are met -
(c) Commanded air fuel ratio 14.8 or more
(d) Heated oxygen sensor voltage 0.21 V or higher, and less than 0.69 V
P0137: Heated Oxygen Sensor Voltage Check (Low Voltage)
Both of the following conditions are met -
(a) Commanded air fuel ratio 14.4 or less
(b) Heated oxygen sensor voltage Less than 0.21 V
P0138: Heated Oxygen Sensor Voltage Check (High Voltage)
Both of the following conditions are met -
(a) Commanded air fuel ratio 14.8 or more
(b) Heated oxygen sensor voltage Higher than 0.69 V

CONFIRMATION DRIVING PATTERN

Tech Tips


  • This confirmation driving pattern is used in the "Perform Confirmation Driving Pattern" procedure of the following diagnostic troubleshooting procedure.

  • Performing this confirmation driving pattern will activate the heated oxygen sensor monitor (the catalyst monitor is performed simultaneously). This is very useful for verifying the completion of a repair.

B006MPFE35

  1. Connect the GTS to the DLC3.

  2. Turn the engine switch on (IG) and turn the GTS on.

  3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).

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

  5. Turn the engine switch on (IG) and turn the GTS on [A].

  6. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher [B].

  7. With the shift lever in D, drive the vehicle at 60 to 100 km/h (37 to 62 mph) for 10 minutes or more [C].

    CAUTION:

    When performing the confirmation driving pattern, obey all speed limits and traffic laws.

  8. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [D].

  9. Read the pending DTCs.

    Tech Tips


    • If a pending DTC is output, the system is malfunctioning.

    • If a pending DTC is not output, perform the following procedure.

  10. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

  11. Input the DTC: P0136, P0137 or P0138.

  12. Check the DTC judgment result.

    GTS Display Description
    NORMAL
    • DTC judgment completed

    • System normal

    ABNORMAL
    • DTC judgment completed

    • System abnormal

    INCOMPLETE
    • DTC judgment not completed

    • Perform driving pattern after confirming DTC enabling conditions

    N/A
    • Unable to perform DTC judgment

    • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    Tech Tips


    • If the judgment result shows NORMAL, the system is normal.

    • If the judgment result shows ABNORMAL, the system has a malfunction.

    • If the judgment result shows INCOMPLETE or N/A, perform steps [C] and [D] again.

WIRING DIAGRAM

B006O0VE01

CAUTION / NOTICE / HINT

Tech Tips

Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F Sensor function provided in the Active Test. The Control the Injection Volume for A/F Sensor function can help to determine whether the air fuel ratio sensor, heated oxygen sensor and other potential trouble areas are malfunctioning.

The following instructions describe how to conduct the Control the Injection Volume for A/F Sensor operation using the GTS.


  1. Connect the GTS to the DLC3.

  2. Start the engine.

  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 and ECT / Active Test / Control the Injection Volume for A/F Sensor / Data List / All Data / AFS Voltage B1S1 and O2S B1S2.

  6. Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).

  7. Monitor the output voltages of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2) displayed on the GTS.

Tech Tips


  • The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.

  • Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

GTS Display (Sensor) Injection Volume Status Voltage

AFS Voltage B1S1

(Air fuel ratio)

12.5% Rich Below 3.1 V
-12.5% Lean Higher than 3.4 V

O2S B1S2

(Heated oxygen)

12.5% Rich Higher than 0.55 V
-12.5% Lean Below 0.4 V

Note

The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.

B006L81E20

Note

Inspect the fuses for circuits related to this system before performing the following procedure.

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. 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. READ OUTPUT DTC (DTC P0136, P0137 OR P0138)


    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 and ECT / Trouble Codes.

    5. Read the DTCs.


      Powertrain > Engine > Trouble Codes
      Result
      Result Proceed to
      DTC P0138 is output A
      DTC P0137 is output B
      DTC P0136 is output C
      DTC P0136, P0137 or P0138 and other DTCs are output D

      Tech Tips

      If any DTCs other than P0136, P0137 or P0138 are output, troubleshoot those DTCs first.


    B
    C
    D
    A
  2. READ VALUE USING GTS (O2S B1S2)


    1. Connect the GTS to the DLC3.

    2. Start the engine.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / O2S B1S2.


      Powertrain > Engine > Data List
      Tester Display
      O2S B1S2
    5. Allow the engine to idle.

    6. Read the heated oxygen sensor output voltage while idling.

      Result
      Heated Oxygen Sensor Output Voltage Proceed to
      1.0 V or higher A
      Less than 1.0 V B

    B
    A
  3. INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)

    B006QC1C06
    *a

    Component without harness connected

    (Heated Oxygen Sensor)


    1. Disconnect the heated oxygen sensor connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      2 (+B) - 3 (OX1B) Always 10 kΩ or higher
      2 (+B) - 4 (E2) Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG
    OK
  4. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)


    1. Turn the engine switch off and wait for 5 minutes or more.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      D1-55 (HT1B) - D1-99 (OX1B) Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK
    NG
  5. PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)


    1. Connect the GTS to the DLC3.

    2. Start the engine.

    3. Turn the GTS on.

    4. Warm up the engine.

    5. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / Data List / All Data / AFS Voltage B1S1 and O2S B1S2.


      Powertrain > Engine > Active Test
      Active Test Display
      Control the Injection Volume for A/F Sensor
      Data List Display
      AFS Voltage B1S1
      O2S B1S2
    6. Change the fuel injection volume using the GTS, and monitor the voltage output of the air fuel ratio and heated oxygen sensors displayed on the GTS.

      Tech Tips


      • The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.

      • The air fuel ratio sensor is displayed as AFS Voltage B1S1, and the heated oxygen sensor is displayed as O2S B1S2 on the GTS.

      • The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.

      • If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

      Result
      GTS Display (Sensor) Voltage Variation Proceed to
      AFS Voltage B1S1 (Air fuel ratio) Alternates between higher and less than 3.3 V OK
      Remains at higher than 3.3 V NG
      Remains at less than 3.3 V

      Tech Tips

      A normal heated oxygen sensor voltage (O2S B1S2) reacts in accordance with increases and decreases in fuel injection volumes. When the air fuel ratio sensor voltage (AFS Voltage B1S1) remains at either less or higher than 3.3 V despite the heated oxygen sensor indicating a normal reaction, the air fuel ratio sensor is malfunctioning.

      B006L2QE01

    NG
    OK
  6. INSPECT AIR FUEL RATIO SENSOR

    Tech Tips

    This air fuel ratio sensor test is to check the air fuel ratio sensor current during the fuel cut operation. When the sensor is normal, the sensor current will indicate less than 2.2 mA in this test.


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Clear the DTCs.


      Powertrain > Engine > Clear DTCs
    5. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

    6. Drive the vehicle at 60 km/h (37 mph) or more for 10 minutes or more.

      CAUTION:

      When performing the confirmation driving pattern, obey all speed limits and traffic laws.

    7. Stop the vehicle.

    8. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / AFS Current B1S1.


      Powertrain > Engine > Data List
      Tester Display
      AFS Current B1S1
    9. Drive the vehicle at 60 km/h (37 mph) or more and release the accelerator pedal for at least 5 seconds without depressing the brake pedal in order to execute fuel-cut control. Perform this 3 times.

      CAUTION:

      When performing the confirmation driving pattern, obey all speed limits and traffic laws.

      B006OVVE43
      Driving Pattern
      *a 60 km/h
      *b 0 km/h
      *c 10 minutes or more
      *d 5 seconds or more
    10. Read the value of the air fuel ratio sensor current while the fuel-cut operation is performed.

      Standard Current
      Less than 2.2 mA

      Tech Tips


      • To measure the air fuel ratio sensor current precisely, perform the fuel-cut operation as long as possible.

      • If it is difficult to measure the air fuel ratio sensor current, use the snapshot function of the GTS.

      Result
      Proceed to
      OK
      NG

    OK
    NG
  7. PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)


    1. Connect the GTS to the DLC3.

    2. Start the engine.

    3. Turn the GTS on.

    4. Warm up the engine.

    5. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / Data List / All Data / O2S B1S2.


      Powertrain > Engine > Active Test
      Active Test Display
      Control the Injection Volume for A/F Sensor
      Data List Display
      O2S B1S2
    6. Change the fuel injection volume using the GTS, and monitor the voltage output of the heated oxygen sensor displayed on the GTS.

      Tech Tips


      • The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.

      • The heated oxygen sensor has a maximum output delay of approximately 20 seconds.

      Standard Voltage
      Fluctuates between 0.4 V or less, and 0.55 V or higher.
      Result
      Proceed to
      OK
      NG

    NG
    OK
  8. PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)


    1. Connect the GTS to the DLC3.

    2. Start the engine.

    3. Turn the GTS on.

    4. Warm up the engine.

    5. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / Data List / All Data / AFS Voltage B1S1 and O2S B1S2.


      Powertrain > Engine > Active Test
      Active Test Display
      Control the Injection Volume for A/F Sensor
      Data List Display
      AFS Voltage B1S1
      O2S B1S2
    6. Change the fuel injection volume using the GTS, and monitor the voltage output of the air fuel ratio sensor and heated oxygen sensor displayed on the GTS.

      Tech Tips


      • The Control the Injection Volume for A/F Sensor operation lowers the fuel injection volume by 12.5% or increases the injection volume by 12.5%.

      • The air fuel ratio sensor is displayed as AFS Voltage B1S1, and the heated oxygen sensor is displayed as O2S B1S2 on the GTS.

      • The air fuel ratio sensor has an output delay of a few seconds and the heated oxygen sensor has a maximum output delay of approximately 20 seconds.

      • If the sensor output voltage does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

      Result
      GTS Display (Sensor) Voltage Variation Proceed to
      AFS Voltage B1S1 (Air fuel ratio) Alternates between higher and less than 3.3 V OK
      Remains at higher than 3.3 V NG
      Remains at less than 3.3 V

      Tech Tips

      A normal heated oxygen sensor voltage (O2S B1S2) reacts in accordance with increases and decreases in fuel injection volumes. When the air fuel ratio sensor voltage (AFS Voltage B1S1) remains at either less or higher than 3.3 V despite the heated oxygen sensor indicating a normal reaction, the air fuel ratio sensor is malfunctioning.

      B006L2QE01

    OK
    NG
  9. REPLACE AIR FUEL RATIO SENSOR


    1. Replace the air fuel ratio sensor.

      Click here

      Tech Tips

      Perform "Inspection After Repair" after replacing the air fuel ratio sensor.

      Click here

      Result
      Proceed to
      NEXT

    NEXT
  10. PERFORM CONFIRMATION DRIVING PATTERN


    1. Perform the Confirmation Driving Pattern.

      Result
      Proceed to
      NEXT

    NEXT
  11. CHECK WHETHER DTC OUTPUT RECURS (DTC P0136 OR P0138)


    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 and ECT / Utility / All Readiness.


      Powertrain > Engine > Utility
      Tester Display
      All Readiness
    5. Input the DTC: P0136 or P0138.

    6. Check that the DTC monitor is NORMAL. If the DTC monitor is INCOMPLETE, perform the driving pattern again but increase the vehicle speed.

      Result
      Result Proceed to

      NORMAL

      (DTCs are not output)

      A

      ABNORMAL

      (DTC P0136 or P0138 is output)

      B

    A
    B
  12. CHECK FOR EXHAUST GAS LEAK


    1. Check for exhaust gas leaks.

      OK
      No gas leaks.

      Tech Tips

      Perform "Inspection After Repair" after repairing or replacing the exhaust system.

      Click here

      Result
      Proceed to
      OK
      NG

    NG
    OK
  13. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)


    1. Inspect the heated oxygen sensor.

      Click here

      Result
      Proceed to
      OK
      NG

    NG
    OK
  14. CHECK HARNESS AND CONNECTOR (HEATED OXYGEN SENSOR - ECM)


    1. Disconnect the heated oxygen sensor connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      D19-1 (HT1B) - D1-55 (HT1B) Always Below 1 Ω
      D19-3 (OX1B) - D1-99 (OX1B) Always Below 1 Ω
      D19-4 (E2) - D1-131 (EX1B) Always Below 1 Ω
      D19-1 (HT1B) or D1-55 (HT1B) - Body ground and other terminals Always 10 kΩ or higher
      D19-3 (OX1B) or D1-99 (OX1B) - Body ground and other terminals Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG
    OK
  15. REPLACE HEATED OXYGEN SENSOR


    1. Replace the heated oxygen sensor.

      Click here

      Result
      Proceed to
      NEXT

    NEXT
  16. PERFORM CONFIRMATION DRIVING PATTERN


    1. Perform Confirmation Driving Pattern.

      Result
      Proceed to
      NEXT

    NEXT
  17. CHECK WHETHER DTC OUTPUT RECURS (DTC P0136, P0137 OR P0138)


    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 and ECT / Utility / All Readiness.


      Powertrain > Engine > Utility
      Tester Display
      All Readiness
    5. Input DTC: P0136, P0137 or P0138.

    6. Check that the DTC monitor is NORMAL. If the DTC monitor is INCOMPLETE, perform the driving pattern again but increase the vehicle speed.

      Result
      Result Proceed to

      NORMAL

      (DTCs are not output)

      A

      ABNORMAL

      (DTC P0136, P0137 or P0138 is output)

      B

      Tech Tips

      Perform "Inspection After Repair" after replacing the air fuel ratio sensor.

      Click here


    A
    B