SFI SYSTEM(for Rear Heated Oxygen Sensor), 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

Tech Tips

Although the DTC titles say oxygen sensor, these DTCs relate to the air fuel ratio sensor.

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

  • Port fuel injector assembly

  • Direct fuel injector assembly

  • Fuel pressure (for low pressure side)

  • Fuel pressure (for high pressure side)

  • Fuel system

  • Fuel pump (for low pressure side)

  • Gas leak from exhaust system

  • ECM

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

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.

B007Y6FE55

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 7 gm/sec or more, and less than 35.9 gm/sec

CONFIRMATION DRIVING PATTERN

Tech Tips

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

B008025E16

  1. Connect the GTS to the DLC3.

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

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

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

  8. Drive the vehicle at a speed of approximately 60 km/h (37 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.

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

  10. 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.

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

  12. Input the DTC: P2A0026.

  13. 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 and no pending DTC is output, perform the following procedure.

  14. 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.

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

  16. 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.

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

  18. Input the DTC: P2A0026.

  19. 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, 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.

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


    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 / 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
    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 engine switch on (IG).

    3. Turn the GTS on.

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

    5. 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
    6. Perform the Control the Injection Volume for A/F Sensor operation with the engine idling.

    7. Monitor the voltage outputs of the air fuel ratio sensor and the heated oxygen sensor (A/F (O2) Sensor Voltage B1S1 and 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 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: During Control the Injection Volume for A/F Sensor of the Active Test, 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: During Control the Injection Volume for A/F Sensor of the Active Test, the A/F (O2) Sensor Voltage B1S1 is consistently below 3.1 V, and the O2 Sensor Voltage B1S2 is consistently higher than 0.55 V.

      • Lean/Rich: During Control the Injection Volume for A/F Sensor of the Active Test, the output voltage of the air fuel ratio sensor or heated oxygen sensor alternates correctly.

      Tech Tips

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

      Click here


    B
    C
    A
  3. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A0026)


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

    6. Turn the engine switch on (IG).

    7. Turn the GTS on.

    8. Start the engine and warm it up.

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

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


      Powertrain > Engine > Utility
      Tester Display
      All Readiness
    11. Input the DTC: P2A0026.

    12. Check the DTC judgment result.

      Result
      Result Proceed to

      NORMAL

      (DTCs are not output)

      A

      ABNORMAL

      (DTC P2A0026 is output)

      B

    A
    B
  4. 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
    OK
  5. CHECK INTAKE SYSTEM


    1. Check the intake system for vacuum leaks.

      Click here

      OK
      No leaks in the intake system.

      Tech Tips

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

      Click here

      Result
      Proceed to
      OK
      NG

    NG
    OK
  6. 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
  7. CHECK FUEL PRESSURE (FOR LOW PRESSURE SIDE)


    1. Check the fuel pressure (for low pressure side).

      Click here

      Result
      Proceed to
      OK
      NG

    NG
    OK
  8. INSPECT PORT FUEL INJECTOR ASSEMBLY


    1. Inspect the port fuel injector assembly (whether fuel volume is high or low, and whether injection pattern is poor).

      Click here

      Tech Tips

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

      Click here

      Result
      Proceed to
      OK
      NG

    NG
    OK
  9. READ VALUE USING GTS (FUEL PRESSURE (HIGH))


    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 / Data List / Engine Speed, Coolant Temperature and Fuel Pressure (High).


      Powertrain > Engine > Data List
      Tester Display
      Engine Speed
      Coolant Temperature
      Fuel Pressure (High)
    5. Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher with all the accessories switched off.

    6. Read Fuel Pressure (High) with the engine speed at 3000 rpm.

      Standard
      GTS Display Condition Specified Condition
      Fuel Pressure (High)

      Shift lever position: P

      A/C: Off

      Engine warmed up

      Engine Speed: 3000 rpm

      4000 to 8000 kPag
      Result
      Proceed to
      OK
      NG

    NG
    OK
  10. INSPECT DIRECT FUEL INJECTOR ASSEMBLY


    1. Inspect the direct fuel injector assembly.

      Click here

      Tech Tips

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

      Click here

      Result
      Proceed to
      OK
      NG

    OK
    NG
  11. INSPECT FUEL PUMP (FOR LOW PRESSURE SIDE)


    1. Inspect the fuel pump (for low pressure side).

      Click here

      Tech Tips

      Perform "Inspection After Repair" after replacing the fuel pump (for low pressure side).

      Click here

      Result
      Proceed to
      OK
      NG

    OK
    NG
  12. 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
  13. CHECK WHETHER DTC OUTPUT RECURS (DTC P2A0026)


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

    6. Turn the engine switch on (IG).

    7. Turn the GTS on.

    8. Start the engine and warm it up.

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

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


      Powertrain > Engine > Utility
      Tester Display
      All Readiness
    11. Input the DTC: P2A0026.

    12. Check the DTC judgment result.

      Result
      Result Proceed to

      NORMAL

      (DTCs are not output)

      A

      ABNORMAL

      (DTC P2A0026 is output)

      B

    A
    B