SFI SYSTEM (w/o EGR System), Diagnostic DTC:P0136, P0137, P0138

DTC Code DTC Name
P0136 Oxygen Sensor Circuit Malfunction (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

Tech Tips

Sensor 2 refers to the sensor mounted behind the three-way catalytic converter and located far from the engine assembly.

In order to obtain a high purification rate of the carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxide (NOx) components in the exhaust gas, a three-way catalytic converter is used. For the most efficient use of the three-way catalytic converter, 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 three-way catalytic converter, 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 rich. The heated oxygen sensor informs the ECM that the post-three-way catalytic converter 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 becomes lean. The heated oxygen sensor informs the ECM that the post-three-way catalytic converter air fuel ratio is rich (high voltage, i.e. more 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 three-way catalytic converter is rich or lean, and adjusts the fuel injection time 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.

A01JAQTE05
DTC No. DTC Detection Condition Trouble Area
P0136

  • 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 increase to 0.59 V or higher.


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

  • 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 injector assembly

  • PCV valve and hose

  • Intake system
P0137

  • 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 is rich.

  • Heated oxygen sensor (sensor 2) circuit

  • Heated oxygen sensor (sensor 2)

  • Air fuel ratio sensor (sensor 1)

  • Gas leak from exhaust system
P0138

  • 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 0.59 V or higher.


    • (b) Target air fuel ratio is lean.

  • Heated oxygen sensor (sensor 2) circuit

  • Heated oxygen sensor (sensor 2)

  • Air fuel ratio sensor (sensor 1)

  • ECM

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.

A01J8M8E34

  1. Connect the intelligent tester to the DLC3.

  2. Turn the power switch on (IG) and turn the tester on.

  3. Clear the DTCs Click here.

  4. Turn the power switch off and wait for 30 seconds.

  5. Turn the power switch on (IG) and turn the tester on [A].

  6. Put the engine in inspection mode (maintenance mode) Click here.

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

  8. Drive the vehicle at 75 to 120 km/h (47 to 75 mph) for 10 minutes or more [C].

    CAUTION:

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

  9. Enter the following menus: Powertrain / Engine and ECT / DTC [D].

  10. Read the pending DTC.

    Tech Tips


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

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

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

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

  13. Check the DTC judgment result.

    Tester 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 ABNORMAL, the system has a malfunction.

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

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

WIRING DIAGRAM

A01JCCRE08

INSPECTION PROCEDURE

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 intelligent tester.


  1. Connect the intelligent tester to the DLC3.

  2. Turn the power switch on (IG).

  3. Turn the tester on.

  4. Put the engine in inspection mode (maintenance mode) Click here.

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

  6. Idle the engine for 5 minutes or more with park (P) selected.

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

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

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

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 increase and decreases in the fuel injection volume.

Tester Display (Sensor) Injection Volume Status Voltage

AFS Voltage B1S1

(Air fuel ratio)

 12.5% Rich Less than 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 Less than 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.

Case Air Fuel Ratio Sensor (Sensor 1) Output Voltage Heated Oxygen Sensor (Sensor 2) Output Voltage Main Suspected Trouble Area
1 A01JBFKE11 A01JB73E08 A01JBFKE11 A01JCQTE06 -
2 A01JBFKE11 A01JCFGE01 A01JBFKE11 A01JCQTE06

  • Air fuel ratio sensor

  • Air fuel ratio sensor heater

  • Air fuel ratio sensor circuit
3 A01JBFKE11 A01JB73E08 A01JBFKE11 A01JCFGE01

  • Heated oxygen sensor

  • Heated oxygen sensor heater

  • Heated oxygen sensor circuit
4 A01JBFKE11 A01JCFGE01 A01JBFKE11 A01JCFGE01

  • Fuel injector assembly

  • Fuel pressure

  • Gas leak from exhaust system (air fuel ratio extremely rich or lean)

Tech Tips


  • Following the Control the Injection Volume for A/F Sensor procedure enables technicians to check and graph the voltage outputs of both the air fuel ratio and heated oxygen sensors.

  • To display the graph, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / All Data / AFS Voltage B1S1 and O2S B1S2; and then press the graph button on the Data List view.

Note

Inspect the fuses for circuits related to this system before performing the following inspection 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 intelligent tester. 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. READ DTC OUTPUT (DTC P0136, P0137 OR P0138)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / DTC.

    5. Read the DTCs.

      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

    CHECK EXHAUST GAS LEAK Click here

    C

    PERFORM ACTIVE TEST USING INTELLIGENT TESTER (CONTROL THE INJECTION VOLUME FOR A/F SENSOR) Click here

    D

    GO TO DTC CHART Click here

    A

  2. READ VALUE USING INTELLIGENT TESTER (O2S B1S2)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the tester on.

    4. Put the engine in inspection mode (maintenance mode) Click here.

    5. Start the engine.

    6. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.

      Tech Tips

      During charging control, the engine speed is set at idle. Therefore, the engine speed does not increase when depressing the accelerator pedal. In this case, warm up the engine after charging control has completed.

    7. Allow the engine to idle.

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

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

      Result
      Result Proceed to
      1.0 V or more A
      Less than 1.0 V B

    B

    PERFORM ACTIVE TEST USING INTELLIGENT TESTER (CONTROL THE INJECTION VOLUME FOR A/F SENSOR) Click here

    A

  3. INSPECT HEATED OXYGEN SENSOR (CHECK FOR SHORT)


    1. A01J9PSE04
      Text in Illustration
      *a

      Component without harness connected

      (Heated Oxygen Sensor (Sensor 2))

      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) - 4 (E2) Always 10 kΩ or higher
      2 (+B) - 3 (OX1B) Always 10 kΩ or higher

    3. Reconnect the heated oxygen sensor connector.


    NG

    REPLACE HEATED OXYGEN SENSOR Click here

    OK

  4. CHECK HARNESS AND CONNECTOR (CHECK FOR SHORT)


    1. Turn the power 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 (Check for Short)
      Tester Connection Condition Specified Condition
      D28-41 (HT1B) - D28-125 (OX1B) Always 10 kΩ or higher

    4. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM Click here

  5. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the tester on.

    4. Put the engine in inspection mode (maintenance mode) Click here.

    5. Start the engine and warm it up.

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

    7. Change the fuel injection volume using the tester and monitor the voltage output of the air fuel ratio and heated oxygen sensors displayed on the tester.

      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 tester.

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

      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 (AFS Voltage B1S1) voltage remains either less or higher than 3.3 V despite the heated oxygen sensor indicating a normal reaction, the air fuel ratio sensor is malfunctioning.

      A01JBIME39

    NG

    REPLACE AIR FUEL RATIO SENSOR Click here

    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. When the sensor is normal, the sensor current will indicate below 2.2 mA in this test.


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the tester on.

    4. Clear the DTCs Click here.

    5. Put the engine in inspection mode (maintenance mode) Click here.

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

    7. Drive the vehicle at 75 km/h (47 mph) or more for 10 minutes or more.

      CAUTION:

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

    8. Stop the vehicle.

    9. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / AFS Current B1S1 and Fuel Cut Condition.

    10. Drive the vehicle at 75 km/h (47 mph) or more and decelerate the vehicle for 5 seconds or more. Perform this 3 times.

      Tech Tips

      While "Fuel Cut Condition" on the Data List is ON, fuel-cut control is being executed.

      CAUTION:

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

      A01JATDE26

    11. Read the value of the air fuel ratio sensor current while the fuel-cut operation is being performed.

      Standard current
      Below 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 intelligent tester.


    OK

    REPLACE HEATED OXYGEN SENSOR Click here

    NG

    REPLACE AIR FUEL RATIO SENSOR Click here

  7. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the tester on.

    4. Put the engine in inspection mode (maintenance mode) Click here.

    5. Start the engine and warm it up.

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

    7. Change the fuel injection volume using the tester and monitor the voltage output of the heated oxygen sensors displayed on the tester.

      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.

    NG

    CHECK EXHAUST GAS LEAK Click here

    OK

  8. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the tester on.

    4. Put the engine in inspection mode (maintenance mode) Click here.

    5. Start the engine and warm it up.

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

    7. Change the fuel injection volume using the tester and monitor the voltage output of the air fuel ratio and heated oxygen sensors displayed on the tester.

      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 tester.

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

      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 (AFS Voltage B1S1) voltage remains either less or higher than 3.3 V despite the heated oxygen sensor indicating a normal reaction, the air fuel ratio sensor is malfunctioning.

      A01JBIME39

    NG

    REPLACE AIR FUEL RATIO SENSOR Click here

    OK

    CHECK ENGINE TO DETERMINE CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO (FUEL INJECTOR ASSEMBLY, FUEL SYSTEM, INTAKE SYSTEM, ETC.) Click here

  9. CHECK EXHAUST GAS LEAK


    1. Inspect for exhaust gas leaks.

      OK
      No gas leaks.

    NG

    REPAIR OR REPLACE EXHAUST GAS LEAK POINT

    OK

  10. INSPECT HEATED OXYGEN SENSOR (HEATER RESISTANCE)


    1. Inspect the heated oxygen sensor Click here.


    NG

    REPLACE HEATED OXYGEN SENSOR Click here

    OK

  11. 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
      D9-1 (HT1B) - D28-41 (HT1B) Always Below 1 Ω
      D9-3 (OX1B) - D28-125 (OX1B) Always Below 1 Ω
      D9-4 (E2) - D28-102 (O1B-) Always Below 1 Ω
      D9-1 (HT1B) or D28-41 (HT1B) - Body ground Always 10 kΩ or higher
      D9-3 (OX1B) or D28-125 (OX1B) - Body ground Always 10 kΩ or higher

    4. Reconnect the heated oxygen sensor connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  12. REPLACE HEATED OXYGEN SENSOR


    1. Replace the heated oxygen sensor Click here.


    NEXT

  13. PERFORM CONFIRMATION DRIVING PATTERN


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the tester on.

    4. Clear the DTC Click here.

    5. Turn the power switch off and wait for 30 seconds.

    6. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.


    NEXT

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


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

    2. Input the DTCs: P0136, P0137 or P0138.

    3. Check the DTC judgement result is NORMAL. If it is INCOMPLETE, perform the drive pattern adding the vehicle speed.

      Result
      Result Proceed to

      ABNORMAL

      (DTC P0136, P0137 or P0138 is output)

      		 A

      NORMAL

      (DTC is not output)

      		 B

    B

    END

    A

    REPLACE AIR FUEL RATIO SENSOR Click here

  15. REPLACE AIR FUEL RATIO SENSOR


    1. Replace the air fuel ratio sensor Click here.


    NEXT

  16. PERFORM CONFIRMATION DRIVING PATTERN


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the tester on.

    4. Clear the DTC Click here.

    5. Turn the power switch off and wait for 30 seconds.

    6. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.


    NEXT

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


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

    2. Input the DTCs: P0136 or P0138.

    3. Check the DTC judgement result is NORMAL. If it is INCOMPLETE, perform the drive pattern adding the vehicle speed.

      Result
      Result Proceed to

      ABNORMAL

      (DTC P0136 or P0138 is output)

      		 A

      NORMAL

      (DTC is not output)

      		 B

    B

    END

    A

    REPLACE HEATED OXYGEN SENSOR Click here