SFI SYSTEM, Diagnostic DTC:P2A0026

DTC Code DTC Name
P2A0026 O2 Sensor Circuit Range/Performance Bank 1 Sensor 1 Signal Rate of Change Below Threshold

DESCRIPTION

Refer to DTC P21951D.

Click here

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory Note
P2A0026 O2 Sensor Circuit Range/Performance Bank 1 Sensor 1 Signal Rate of Change Below Threshold The calculated value for the air fuel ratio sensor response rate deterioration level is less than the threshold (2 trip detection logic).

  • Air fuel ratio sensor (sensor 1)

  • Intake system

  • Fuel injector assembly

  • Exhaust gas leak

  • Fuel pump

  • Fuel line

  • EGR valve assembly

  • ECM

 Comes on DTC stored SAE Code: P2A00

MONITOR DESCRIPTION

After the engine is warmed up, the ECM performs air fuel ratio feedback control to maintain the air fuel ratio at the stoichiometric level. In addition, active air fuel ratio control is performed for approximately 30 seconds after preconditions are met in order to measure the air fuel ratio sensor response rate. During active air fuel ratio control, the ECM forcibly increases and decreases the injection volume by a certain amount, based on the stoichiometric air fuel ratio learned during normal air fuel ratio control, and measures the air fuel ratio sensor response rate. The ECM receives a signal from the air fuel ratio sensor while performing active air fuel ratio control and uses it to calculate the air fuel ratio sensor response rate deterioration level.

If the value for the air fuel ratio sensor response rate deterioration level is less than the threshold, the ECM interprets this as a malfunction and stores this DTC.

A001RD5E55

MONITOR STRATEGY

Required Sensors/Components Air fuel ratio sensor
Frequency of Operation Once per driving cycle

TYPICAL ENABLING CONDITIONS

Active air fuel ratio control Performing
Active air fuel ratio control performed when following conditions met -
Engine coolant temperature 75°C (167°F) or higher
Idling Off
Engine speed Less than 4000 rpm
Air fuel ratio sensor status Activated
Engine load 10% or higher, and less than 70%
Catalyst monitor Not yet
Mass air flow 6 gm/sec or more, and less than 14 gm/sec

CONFIRMATION DRIVING PATTERN

Tech Tips

Performing this confirmation driving pattern will activate the air fuel ratio sensor response monitor.

A001O5CE28

  1. Connect the GTS to the DLC3.

  2. Turn the power switch on (IG).

  3. Turn the GTS on.

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

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

  6. Turn the power switch on (IG).

  7. Turn the GTS on.

  8. Put the engine in Inspection Mode (Maintenance Mode).

    Click here

  9. Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [A].

  10. With the engine running, drive the vehicle at a speed between 60 and 100 km/h (37 and 62 mph) for 10 minutes or more in a city area [B].

    CAUTION:

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

    Tech Tips

    If the engine stops, further depress the accelerator pedal to restart the engine.

  11. Enter the following menus: Powertrain / Engine / Trouble Codes [C].

  12. 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.

  13. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

  14. Input the DTC: P2A0026.

  15. 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 is NORMAL, the system is normal.

    • If the judgment result is ABNORMAL, the system is malfunctioning.

    • If the judgment result is INCOMPLETE or N/A and no pending DTC is output, perform the following procedure.

  16. With the engine running, drive the vehicle at a speed between 75 and 100 km/h (47 and 62 mph) for 10 minutes [D].

    CAUTION:

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

    Tech Tips

    If the engine stops, further depress the accelerator pedal to restart the engine.

  17. Enter the following menus: Powertrain / Engine / Trouble Codes [E].

  18. 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.

  19. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

  20. Input the DTC: P2A0026.

  21. 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 is NORMAL, the system is normal.

    • If the judgment result is ABNORMAL, the system is malfunctioning.

    • If the judgment result is INCOMPLETE or N/A, drive the vehicle again under an increased load and then recheck the judgment result.

WIRING DIAGRAM

Refer to DTC P21951D.

Click here

CAUTION / NOTICE / HINT

Note

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

Tech Tips


  • DTC P2A0026 may be also stored when the air fuel ratio is stuck at rich or lean.

  • A low air fuel ratio sensor voltage could be caused by a rich air fuel mixture. Check for conditions that would cause the engine to run rich.

  • A high air fuel ratio sensor voltage could be caused by a lean air fuel mixture. Check for conditions that would cause the engine to run lean.

  • 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.

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

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

PROCEDURE


  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P2A0026)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

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

    5. Read the DTCs.


      Powertrain > Engine > Trouble Codes
      Result
      Result Proceed to
      DTC P2A0026 is output A
      DTC P2A0026 and other DTCs are output B

      Tech Tips

      If any DTCs other than P2A0026 are output, troubleshoot those DTCs first.


    B

    GO TO DTC CHART Click here

    A

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


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Put the engine in Inspection Mode (Maintenance Mode).

      Click here


      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 / 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
      A/F (O2) Sensor Voltage B1S1
      O2 Sensor Voltage B1S2

    8. Change the fuel injection volume using the GTS, 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 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 A/F (O2) Sensor Voltage B1S1, and the heated oxygen sensor is displayed as O2 Sensor Voltage 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.

      Standard
      GTS 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

      • 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.

      • 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.

      • 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.

        Tech Tips

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

        Click here


    B

    INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE) Click here

    C

    REPLACE AIR FUEL RATIO SENSOR Click here

    A

  3. CLEAR DTC


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS 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

    NEXT

  4. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A0026)


    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: P2A0026.

    4. Check the DTC judgment result.

      Result
      Result Proceed to

      NORMAL

      (DTC is not output)

      		 A

      ABNORMAL

      (DTC P2A0026 is output)

      		 B

    A

    END

    B

  5. PERFORM ACTIVE TEST USING GTS (CONTROL THE EGR STEP POSITION)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Put the engine in Inspection Mode (Maintenance Mode).

      Click here


      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.

      Tech Tips

      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 and Engine Independent.


      Powertrain > Engine > Active Test
      Active Test Display
      Control the EGR Step Position
      Data List Display
      Intake Manifold Absolute Pressure
      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 (75 mmHg) higher than when EGR valve is fully closed

      Tech Tips


      • 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
      Proceed to
      OK
      NG

    OK

    GO TO STEP 15 Click here

    NG

  6. INSPECT EGR VALVE ASSEMBLY


    1. Remove the EGR valve assembly.

      Click here

    2. Check if the EGR valve is stuck open.

      OK
      EGR valve is tightly closed.

      Tech Tips

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

      Click here

      Result
      Proceed to
      OK
      NG

    OK

    GO TO STEP 15 Click here

    NG

    REPLACE EGR VALVE ASSEMBLY Click here

  7. INSPECT AIR FUEL RATIO SENSOR (HEATER RESISTANCE)


    1. Inspect 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
      OK
      NG

    NG

    REPLACE AIR FUEL RATIO SENSOR Click here

    OK

  8. CHECK INTAKE SYSTEM


    1. Check the intake system for vacuum leaks.

      Click here

      OK
      No leaks from the intake system.

      Tech Tips

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

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE INTAKE SYSTEM

    OK

  9. CHECK FOR EXHAUST GAS LEAK


    1. Check for exhaust gas leaks.

      OK
      No gas leaks in exhaust system.

      Tech Tips

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

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE EXHAUST SYSTEM

    OK

  10. PERFORM ACTIVE TEST USING GTS (CONTROL THE EGR STEP POSITION)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Put the engine in Inspection Mode (Maintenance Mode).

      Click here


      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.

      Tech Tips

      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 and Engine Independent.


      Powertrain > Engine > Active Test
      Active Test Display
      Control the EGR Step Position
      Data List Display
      Intake Manifold Absolute Pressure
      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 (75 mmHg) higher than when EGR valve is fully closed

      Tech Tips


      • 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
      Proceed to
      OK
      NG

    OK

    GO TO STEP 12 Click here

    NG

  11. INSPECT EGR VALVE ASSEMBLY


    1. Remove the EGR valve assembly.

      Click here

    2. Check if the EGR valve is stuck open.

      OK
      EGR valve is tightly closed.

      Tech Tips

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

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    REPLACE EGR VALVE ASSEMBLY Click here

    OK

  12. CHECK FUEL PRESSURE


    1. Check the fuel pressure.

      Click here

      Result
      Proceed to
      OK
      NG

    NG

    INSPECT FUEL PUMP Click here

    OK

  13. INSPECT FUEL INJECTOR ASSEMBLY


    1. Inspect the fuel injector assembly.

      Click here

      Tech Tips

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

      Click here

      Result
      Proceed to
      OK
      NG

    OK

    GO TO STEP 15 Click here

    NG

    REPLACE FUEL INJECTOR ASSEMBLY Click here

  14. INSPECT FUEL PUMP


    1. Inspect the fuel pump.

      Click here

      Tech Tips

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

      Click here

      Result
      Proceed to
      OK
      NG

    OK

    REPAIR OR REPLACE FUEL LINE

    NG

    REPLACE FUEL PUMP Click here

  15. 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

  16. CLEAR DTC


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS 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

    NEXT

  17. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A0026)


    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: P2A0026.

    4. Check the DTC judgment result.

      Result
      Result Proceed to

      NORMAL

      (DTC is not output)

      		 A

      ABNORMAL

      (DTC P2A0026 is output)

      		 B

    A

    END

    B

    REPLACE ECM Click here