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Home >> Toyota >> 2021 >> Highlander LE, 4WD >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 52 (Engine Control System (A25A-FXS) - Diagnostic Codes (P0128-P0171)) >> SFI System >> DTC P014C-00: O2 Sensor Slow Response - Rich to Lean Bank 1 Sensor 1; DTC P014D-00: O2 Sensor Slow Response - Lean to Rich Bank 1 Sensor 1; DTC P015A-00: O2 Sensor Delayed Response - Rich to Lean Bank 1 Sensor 1; DTC P015B-00: O2 Sensor Delayed Response - Lean to Rich Bank 1 Sensor 1 [11/2023 - ] >> Procedure

DTC P014C-00: O2 Sensor Slow Response - Rich to Lean Bank 1 Sensor 1; DTC P014D-00: O2 Sensor Slow Response - Lean to Rich Bank 1 Sensor 1; DTC P015A-00: O2 Sensor Delayed Response - Rich to Lean Bank 1 Sensor 1; DTC P015B-00: O2 Sensor Delayed Response - Lean to Rich Bank 1 Sensor 1 [11/2023 - ]: Procedure

WARNING: This page is about a different variant/trim than selected.
  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P014C-00, P014D-00, P015A-00 OR P015B-00) 
    1. Read the DTCs.

      Powertrain > Engine > Trouble Codes 

      Result

      Result Proceed to
      DTC P014C-00, P014D-00, P015A-00 or P015B-00 is output A
      DTC P014C-00, P014D-00, P015A-00 or P015B-00 and other DTCs are output B

      HINT: 

      If any DTCs other than P014C-00, P014D-00, P015A-00 or P015B-00 are output, troubleshoot those DTCs first.

    Result: 

    B 

    GO TO DTC CHART  . Refer to DIAGNOSTIC TROUBLE CODE CHART [11/2023 - 11/2024] , or refer to DIAGNOSTIC TROUBLE CODE CHART [11/2024 - ]

    Result: 

    A 

    See step  2

  2. INSPECT AIR FUEL RATIO SENSOR (SENSOR 1) (HEATER RESISTANCE) 

    Refer to INSPECTION [12/2019 - ]

    HINT: 

    Perform "Inspection After Repair" after replacing the air fuel ratio sensor (sensor 1).

    Refer to INITIALIZATION [10/2021 - ]

    Result

    Proceed to
    OK
    NG

    Result: 

    NG 

    REPLACE AIR FUEL RATIO SENSOR (SENSOR 1) 

    Refer to REMOVAL [12/2019 - ]

    Result: 

    OK 

    See step  3

  3. CHECK HARNESS AND CONNECTOR (AIR FUEL RATIO SENSOR (SENSOR 1) - ECM) 
    1. Disconnect the air fuel ratio sensor (sensor 1) 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
      C45-1 (HA1A) - C55-9 (HA1A) Always Below 1 Ω
      C45-3 (A1A+) - C55-95 (A1A+) Always Below 1 Ω
      C45-4 (A1A-) - C55-94 (A1A-) Always Below 1 Ω
      C45-1 (HA1A) or C55-9 (HA1A) - Body ground and other terminals Always 10 kΩ or higher
      C45-3 (A1A+) or C55-95 (A1A+) - Body ground and other terminals Always 10 kΩ or higher
      C45-4 (A1A-) or C55-94 (A1A-) - Body ground and other terminals Always 10 kΩ or higher

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Result: 

    OK 

    See step  4

  4. CLEAR DTC 
    1. Clear the DTCs.

      Powertrain > Engine > Clear DTCs 

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

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  5

  5. CHECK WHETHER DTC OUTPUT RECURS (DTC P014C-00, P014D-00, P015A-00 OR P015B-00) 
    1. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    2. Read the pending DTCs.

      Powertrain > Engine > Trouble Codes 

      Result

      Result Proceed to
      DTCs are not output A
      DTC P014C-00, P014D-00, P015A-00 or P015B-00 is output B

    Result: 

    A 

    CHECK FOR INTERMITTENT PROBLEMS 

    Refer to CHECK FOR INTERMITTENT PROBLEMS [12/2019 - ]

    Result: 

    B 

    See step  6

  6. REPLACE AIR FUEL RATIO SENSOR (SENSOR 1) 

    Refer to REMOVAL [12/2019 - ]

    HINT: 

    Perform "Inspection After Repair" after replacing the air fuel ratio sensor (sensor 1).

    Refer to INITIALIZATION [10/2021 - ]

    Result

    Proceed to
    NEXT

    Result: 

    NEXT 

    See step  7

  7. CLEAR DTC 
    1. Clear the DTCs.

      Powertrain > Engine > Clear DTCs 

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

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  8

  8. CHECK WHETHER DTC OUTPUT RECURS (DTC P014C-00, P014D-00, P015A-00 OR P015B-00) 
    1. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    2. Read the pending DTCs.

      Powertrain > Engine > Trouble Codes 

      Result

      Result Proceed to
      DTCs are not output A
      DTC P014C-00, P014D-00, P015A-00 or P015B-00 is output B

    Result: 

    A 

    END 

    Result: 

    B 

    CHECK ENGINE TO DETERMINE CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO 

    Refer to DTC P0171-00: System Too Lean Bank 1; DTC P0172-00: System Too Rich Bank 1; DTC P1170-00: Fuel Performance/Port Injector; DTC P117B-00: Fuel Performance/Direct Injector [11/2023 - ]

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