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Home >> Toyota >> 2019 >> Prius LE >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System - Diagnostic Codes (8 Of 8) & Circuit Tests >> SFI System >> DTC P2A00-26: O2 Sensor Circuit Range/Performance Bank 1 Sensor 1 Signal Rate of Change Below Threshold [07/2020 - ] >> Procedure
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DTC P2A00-26: O2 Sensor Circuit Range/Performance Bank 1 Sensor 1 Signal Rate of Change Below Threshold [07/2020 - ]: Procedure

  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P2A00-26) 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Trouble Codes.
    5. Read the DTCs.

      Powertrain > Engine > Trouble Codes 

      Result

      Result Proceed to
      DTC P2A00-26 is output A
      DTC P2A00-26 and other DTCs are output B

      HINT: 

      If any DTCs other than P2A00-26 are output, troubleshoot those DTCs first.

    Result: 

    B 

    GO TO DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [07/2020 - ] 

    Result: 

    A 

    See step  2

  2. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME FOR A/F SENSOR) 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Turn the Techstream on.
    4. Put the engine in Inspection Mode (Maintenance Mode).

      Powertrain > Hybrid Control > Utility 

      Tester Display
      Inspection Mode
    5. Start the engine and warm it up until the engine coolant temperature is 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 / Active Test / Control the Injection Volume for A/F Sensor / Data List / Injection Volume, A/F (O2) Sensor Voltage B1S1 and O2 Sensor Voltage B1S2.

      Powertrain > Engine > Active Test 

      Active Test Display
      Control the Injection Volume for A/F Sensor
      Data List Display
      Injection Volume
      A/F (O2) Sensor Voltage B1S1
      O2 Sensor Voltage B1S2
    8. Change the fuel injection volume using the Techstream, and monitor the output voltage of the air fuel ratio sensor (A/F (O2) Sensor Voltage B1S1) and heated oxygen sensor (O2 Sensor Voltage B1S2) displayed on the Techstream.

      HINT: 

      • 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 A/F (O2) Sensor Voltage B1S1, and the heated oxygen sensor is displayed as O2 Sensor Voltage B1S2 on the Techstream.
      • 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.

      Standard

      Techstream Display (Sensor) Injection Volume Status Voltage
      A/F (O2) Sensor Voltage B1S1
      (Air fuel ratio)      		 12.5% Rich Below 3.1 V
      -12.5% Lean Higher than 3.4 V
      O2 Sensor Voltage B1S2
      (Heated oxygen)      		 12.5% Rich Higher than 0.55 V
      -12.5% Lean Below 0.4 V

      Result

      Status of A/F (O2) Sensor Voltage B1S1 Status of O2 Sensor Voltage B1S2 Air Fuel Ratio Condition and Air Fuel Ratio Sensor Condition Proceed to
      Lean/Rich Lean/Rich Normal A
      Lean Lean Actual air fuel ratio lean B
      Rich Rich Actual air fuel ratio rich
      Lean Lean/Rich Air fuel ratio sensor malfunction C
      Rich Lean/Rich Air fuel ratio sensor malfunction
      1. Lean: While performing the Active Test "Control the Injection Volume for A/F Sensor", the air fuel ratio sensor output voltage (A/F (O2) Sensor Voltage B1S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2 Sensor Voltage B1S2) is consistently below 0.4 V.
      2. Rich: While performing the Active Test "Control the Injection Volume for A/F Sensor", the air fuel ratio sensor output voltage (A/F (O2) Sensor Voltage B1S1) is consistently below 3.1 V, and the heated oxygen sensor output voltage (O2 Sensor Voltage B1S2) is consistently higher than 0.55 V.
      3. Lean/Rich: While performing the Active Test "Control the Injection Volume for A/F Sensor", the output voltage of the fuel ratio sensor (A/F (O2) Sensor Voltage B1S1) or heated oxygen sensor (O2 Sensor Voltage B1S2) alternates correctly.

        HINT: 

        Refer to "Data List / Active Test" [A/F (O2) Sensor Voltage B1S1 and O2 Sensor Voltage B1S2].

        Refer to DATA LIST / ACTIVE TEST [07/2020 - ]

    Result: 

    B 

    See step  7

    Result: 

    C 

    See step  15

    Result: 

    A 

    See step  3

  3. CLEAR DTC 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Turn the Techstream on.
    4. Clear the DTCs.

      Powertrain > Engine > Clear DTCs 

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

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  4

  4. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00-26) 
    1. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    2. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

      Powertrain > Engine > Utility 

      Tester Display
      All Readiness
    3. Input the DTC: P2A00-26.
    4. Check the DTC judgment result.

      Result

      Result Proceed to
      NORMAL
      (DTC is not output)      		 A
      ABNORMAL
      (DTC P2A00-26 is output)      		 B

    Result: 

    A 

    END 

    Result: 

    B 

    See step  5

  5. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE EGR STEP POSITION) 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Turn the Techstream on.
    4. Put the engine in Inspection Mode (Maintenance Mode).

      Powertrain > Hybrid Control > Utility 

      Tester Display
      Inspection Mode
    5. Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher.

      HINT: 

      The A/C switch and all accessories should be off.

    6. Enter the following menus: Powertrain / Engine / Active Test / Control the EGR Step Position / Data List / Intake Manifold Absolute Pressure, EGR Step Position and Engine Independent.

      Powertrain > Engine > Active Test 

      Active Test Display
      Control the EGR Step Position
      Data List Display
      Intake Manifold Absolute Pressure
      EGR Step Position
      Engine Independent
    7. Confirm that the value of Data List item Engine Independent is "Operate" then check the value of Intake Manifold Absolute Pressure while performing the Active Test.
      NOTE:
      • Do not leave the EGR valve open for 10 seconds or more during the Active Test.
      • Be sure to return the EGR valve to step 0 when the Active Test is completed.
      • Do not open the EGR valve 30 steps or more during the Active Test.

      OK

      The value of Intake Manifold Absolute Pressure changes in response to the EGR step position when the value of Engine Independent is "Operate".

      Standard

      - Control the EGR Step Position (Active Test)
      0 Steps 0 to 30 Steps
      Intake Manifold Absolute Pressure
      (Data List)      		 (EGR valve is fully closed) Intake Manifold Absolute Pressure value is at least +10 kPa (1.45 psi) higher than when EGR valve is fully closed

      HINT: 

      • If the value of Data List item Engine Independent is "Not Opr" when the engine is idling, charge control is being performed. Perform the Active Test after charge control is complete ("Operate" is displayed).
      • While performing the Active Test, if the increase in the value of Intake Manifold Absolute Pressure is small, the EGR valve assembly may be malfunctioning.
      • Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of Intake Manifold Absolute Pressure may occur while performing the Active Test. However, the amount that the value of Intake Manifold Absolute Pressure increases will be smaller than normal.

      Result

      Result  Proceed to
      The value of Intake Manifold Absolute Pressure increases by 10 kPa(abs) or more, compared to when the EGR valve was fully closed (0 step)  OK
      Other than above  NG

      HINT: 

      10 kPa = 1.45 psi

    Result: 

    OK 

    See step  15

    Result: 

    NG 

    See step  6

  6. INSPECT EGR VALVE ASSEMBLY 
    1. Remove the EGR valve assembly.

      HINT: 

      Refer to REMOVAL [07/2020 - ]

    2. Check if the EGR valve is stuck open.

      OK

      EGR valve is tightly closed.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    See step  15

    Result: 

    NG 

    REPLACE EGR VALVE ASSEMBLY 

    Refer to REMOVAL [07/2020 - ]

    HINT: 

    Perform "Inspection After Repair" after replacing the EGR valve assembly.

    Refer to INITIALIZATION [11/2015 - ]

  7. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE) 
    1. Inspect the air fuel ratio sensor.

      Refer to INSPECTION [11/2015 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE AIR FUEL RATIO SENSOR 

    Refer to REMOVAL [11/2015 - ]

    HINT: 

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

    Refer to INITIALIZATION [11/2015 - ]

    Result: 

    OK 

    See step  8

  8. CHECK INTAKE SYSTEM 
    1. Check the intake system for vacuum leaks.

      Refer to ON-VEHICLE INSPECTION [11/2015 - ]

      OK

      No leaks from the intake system.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE INTAKE SYSTEM 

    HINT: 

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

    Refer to INITIALIZATION [11/2015 - ]

    Result: 

    OK 

    See step  9

  9. CHECK FOR EXHAUST GAS LEAK 
    1. Check for exhaust gas leaks.

      OK

      No gas leaks in exhaust system.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE EXHAUST SYSTEM 

    HINT: 

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

    Refer to INITIALIZATION [11/2015 - ]

    Result: 

    OK 

    See step  10

  10. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE EGR STEP POSITION) 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Turn the Techstream on.
    4. Put the engine in Inspection Mode (Maintenance Mode).

      Powertrain > Hybrid Control > Utility 

      Tester Display
      Inspection Mode
    5. Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher.

      HINT: 

      The A/C switch and all accessories should be off.

    6. Enter the following menus: Powertrain / Engine / Active Test / Control the EGR Step Position / Data List / Intake Manifold Absolute Pressure, EGR Step Position and Engine Independent.

      Powertrain > Engine > Active Test 

      Active Test Display
      Control the EGR Step Position
      Data List Display
      Intake Manifold Absolute Pressure
      EGR Step Position
      Engine Independent
    7. Confirm that the value of Data List item Engine Independent is "Operate" then check the value of Intake Manifold Absolute Pressure while performing the Active Test.
      NOTE:
      • Do not leave the EGR valve open for 10 seconds or more during the Active Test.
      • Be sure to return the EGR valve to step 0 when the Active Test is completed.
      • Do not open the EGR valve 30 steps or more during the Active Test.

      OK

      The value of Intake Manifold Absolute Pressure changes in response to the EGR step position when the value of Engine Independent is "Operate".

      Standard

      - Control the EGR Step Position (Active Test)
      0 Steps 0 to 30 Steps
      Intake Manifold Absolute Pressure
      (Data List)      		 (EGR valve is fully closed) Intake Manifold Absolute Pressure value is at least +10 kPa (1.45 psi) higher than when EGR valve is fully closed

      HINT: 

      • If the value of Data List item Engine Independent is "Not Opr" when the engine is idling, charge control is being performed. Perform the Active Test after charge control is complete ("Operate" is displayed).
      • While performing the Active Test, if the increase in the value of Intake Manifold Absolute Pressure is small, the EGR valve assembly may be malfunctioning.
      • Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of Intake Manifold Absolute Pressure may occur while performing the Active Test. However, the amount that the value of Intake Manifold Absolute Pressure increases will be smaller than normal.

      Result

      Result  Proceed to
      The value of Intake Manifold Absolute Pressure increases by 10 kPa(abs) or more, compared to when the EGR valve was fully closed (0 step)  OK
      Other than above  NG

      HINT: 

      10 kPa = 1.45 psi

    Result: 

    OK 

    See step  12

    Result: 

    NG 

    See step  11

  11. INSPECT EGR VALVE ASSEMBLY 
    1. Remove the EGR valve assembly.

      HINT: 

      Refer to REMOVAL [07/2020 - ]

    2. Check if the EGR valve is stuck open.

      OK

      EGR valve is tightly closed.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPLACE EGR VALVE ASSEMBLY 

    Refer to REMOVAL [07/2020 - ]

    HINT: 

    Perform "Inspection After Repair" after replacing the EGR valve assembly.

    Refer to INITIALIZATION [11/2015 - ]

    Result: 

    OK 

    See step  12

  12. CHECK FUEL PRESSURE 
    1. Check the fuel pressure.

      Refer to PROCEDURE - Step 2

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  14

    Result: 

    OK 

    See step  13

  13. INSPECT FUEL INJECTOR ASSEMBLY 
    1. Inspect the fuel injector assembly.

      Refer to INSPECTION [12/2018 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    See step  15

    Result: 

    NG 

    REPLACE FUEL INJECTOR ASSEMBLY 

    Refer to REMOVAL [07/2020 - ]

    HINT: 

    Perform "Inspection After Repair" after replacing the fuel injector assembly.

    Refer to INITIALIZATION [11/2015 - ]

  14. INSPECT FUEL PUMP 
    1. Inspect the fuel pump.

      Refer to INSPECTION [12/2018 - ]

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    REPAIR OR REPLACE FUEL LINE 

    Result: 

    NG 

    REPLACE FUEL PUMP 

    Refer to REMOVAL [07/2020 - ]

    HINT: 

    Perform "Inspection After Repair" after replacing the fuel pump.

    Refer to INITIALIZATION [11/2015 - ]

  15. REPLACE AIR FUEL RATIO SENSOR 
    1. Replace the air fuel ratio sensor.

      HINT: 

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  16

  16. CLEAR DTC 
    1. Connect the Techstream to the DLC3.
    2. Turn the power switch on (IG).
    3. Turn the Techstream on.
    4. Clear the DTCs.

      Powertrain > Engine > Clear DTCs 

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

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  17

  17. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A00-26) 
    1. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    2. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

      Powertrain > Engine > Utility 

      Tester Display
      All Readiness
    3. Input the DTC: P2A00-26.
    4. Check the DTC judgment result.

      Result

      Result Proceed to
      NORMAL
      (DTC is not output)      		 A
      ABNORMAL
      (DTC P2A00-26 is output)      		 B

    Result: 

    A 

    END 

    Result: 

    B 

    REPLACE ECM. Refer to  REMOVAL [07/2020 - ] 

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