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Home >> Toyota >> 2017 >> Corolla XLE >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Control System (2ZR-FE) - Diagnostic Codes (3 Of 7) (Model Code: ZRE172) >> SFI System >> DTC P0420: Catalyst System Efficiency Below Threshold (Bank 1) [08/2014 - 08/2016] >> Procedure
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DTC P0420: Catalyst System Efficiency Below Threshold (Bank 1) [08/2014 - 08/2016]: Procedure

  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420) 
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch to ON.
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
    5. Read the DTCs.

      Powertrain > Engine and ECT > Trouble Codes 

      Result

      Result Proceed to
      DTC P0420 is output A
      DTC P0420 and other DTCs are output B

      HINT: 

      If any DTCs other than P0420 are output, troubleshoot those DTCs first.

    Result:  2

    B 

    GO TO DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [08/2014 - 08/2015]  Refer to  DIAGNOSTIC TROUBLE CODE CHART [08/2015 - 08/2016] 

    Result:  1

    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. Start the engine and warm it up.
    3. Turn the Techstream on.
    4. Run the engine at an engine speed of 2500 rpm for approximately 90 seconds.
    5. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor / Gas AF Control / AFS Voltage B1S1 and O2S B1S2.

      Powertrain > Engine and ECT > Active Test 

      Active Test Display
      Control the Injection Volume for A/F Sensor
      Data List Display
      AFS Voltage B1S1
      O2S B1S2
    6. Perform the Active Test operation with the engine idling (press the 12.5% or -12.5% button to change the fuel injection volume).
    7. Monitor the voltage outputs of the air fuel ratio sensor and heated oxygen sensor (AFS Voltage B1S1 and O2S 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%.
      • Each sensor reacts in accordance with increases and decreases in the fuel injection volume.
      • 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
      AFS Voltage B1S1
      (Air fuel ratio)      		 12.5% Rich Below 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 Below 0.4 V

      Result

      Status AFS Voltage B1S1 Status O2S B1S2 Actual air fuel ratio, air fuel ratio sensor and heated oxygen sensor condition Misfire Main Suspected Trouble Area Proceed to
      Lean/Rich Lean/Rich Normal -
      • Three-way catalytic converter
      • Gas leak from exhaust system
      		 A
      Lean Lean/Rich Air fuel ratio sensor malfunction -
      • Air fuel ratio sensor
      		 B
      Rich Lean/Rich Air fuel ratio sensor malfunction -
      • Air fuel ratio sensor
      Lean/Rich Lean Heated oxygen sensor malfunction -
      • Heated oxygen sensor
      • Gas leak from exhaust system
      		 C
      Lean/Rich Rich Heated oxygen sensor malfunction -
      • Heated oxygen sensor
      • Gas leak from exhaust system
      Lean Lean Actual air fuel ratio lean May occur
      • Extremely lean actual air fuel ratio
      • Gas leak from exhaust system
      		 D
      Rich Rich Actual air fuel ratio rich -
      • Extremely rich actual air fuel ratio
      • Gas leak from exhaust system
      • Lean: During Control the Injection Volume for A/F Sensor Active Test, the air fuel ratio sensor output voltage (AFS Voltage B1S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S B1S2) is consistently below 0.4 V.
      • Rich: During Control the Injection Volume for A/F Sensor Active Test, AFS Voltage B1S1 is consistently below 3.1 V, and O2S B1S2 is consistently higher than 0.55 V.
      • Lean/Rich: During Control the Injection Volume for A/F Sensor Active Test, the output voltage of the air fuel ratio sensor and heated oxygen sensor alternate correctly.

      HINT: 

      Refer to "Data List / Active Test" [AFS Voltage B1S1 and O2S B1S2].

      Refer to DATA LIST / ACTIVE TEST [08/2014 - 08/2016]

    Result:  2

    B 

    See step  8

    Result:  3

    C 

    See step  9

    Result:  4

    D 

    See step  11

    Result:  1

    A 

    See step  3

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

      OK

      No gas leaks.

      Result

      Proceed to
      OK
      NG

    Result:  2

    NG 

    See step  5

    Result:  1

    OK 

    See step  4

  4. REPLACE FRONT EXHAUST PIPE ASSEMBLY (TWC: FRONT AND REAR CATALYST) 
    NOTE:

    Replace the front exhaust pipe assembly (TWC: Front and rear catalyst) when catalyst replacement is necessary.

    HINT: 

    Confirm the replacement parts, referring to the illustration in the Catalyst Location.

    1. Replace the front exhaust pipe assembly (TWC: Front and rear catalyst).

      Refer to COMPONENTS [08/2013 - ]

      Result

      Proceed to
      NEXT

    Result:  1

    NEXT 

    END 

  5. REPAIR OR REPLACE EXHAUST GAS LEAK POINT 
    1. Repair or replace exhaust gas leak point.

      HINT: 

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

      Refer to INITIALIZATION [08/2013 - 08/2016]

      Result

      Proceed to
      NEXT

    Result:  1

    NEXT 

    See step  6

  6. CHECK WHETHER DTC OUTPUT RECURS (DTC P0420) 
    1. Connect the Techstream to the DLC3.
    2. Turn the ignition switch to ON.
    3. Turn the Techstream on.
    4. Clear the DTCs.

      Refer to DTC CHECK / CLEAR [08/2013 - ]

      Powertrain > Engine and ECT > Clear DTCs 

    5. Turn the ignition switch off and wait for at least 30 seconds.
    6. Turn the ignition switch to ON.
    7. Turn the Techstream on.
    8. Start the engine.
    9. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    10. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
    11. Read the DTCs.

      Powertrain > Engine and ECT > Trouble Codes 

      Result

      Result Proceed to
      DTC P0420 is output A
      DTCs are not output
      (Pending DTC is not output)      		 B

    Result:  2

    B 

    END 

    Result:  1

    A 

    See step  7

  7. REPLACE FRONT EXHAUST PIPE ASSEMBLY (TWC: FRONT AND REAR CATALYST) 
    NOTE:

    Replace the front exhaust pipe assembly (TWC: Front and rear catalyst) when catalyst replacement is necessary.

    HINT: 

    Confirm the replacement parts, referring to the illustration in the Catalyst Location.

    1. Replace the front exhaust pipe assembly (TWC: Front and rear catalyst).

      Refer to COMPONENTS [08/2013 - ]

      Result

      Proceed to
      NEXT

    Result:  1

    NEXT 

    END 

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

      Refer to REMOVAL [08/2013 - ]

      HINT: 

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

      Refer to INITIALIZATION [08/2013 - 08/2016]

      Result

      Proceed to
      NEXT

    Result:  1

    NEXT 

    See step  6

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

      OK

      No gas leaks.

      Result

      Proceed to
      OK
      NG

    Result:  2

    NG 

    See step  5

    Result:  1

    OK 

    See step  10

  10. REPLACE HEATED OXYGEN SENSOR 
    1. Replace the heated oxygen sensor.

      Refer to REMOVAL [08/2013 - ]

      HINT: 

      Perform "Inspection After Repair" after replacing the heated oxygen sensor.

      Refer to INITIALIZATION [08/2013 - 08/2016]

      Result

      Proceed to
      NEXT

    Result:  1

    NEXT 

    See step  6

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

      OK

      No gas leaks.

      Result

      Proceed to
      OK
      NG

    Result:  2

    NG 

    See step  5

    Result:  1

    OK 

    See step  12

  12. CHECK CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO 
    1. Check the cause of extremely rich or lean actual air fuel ratio, referring to the DTC P0171 and P0172 Inspection Procedure.

      Refer to DTC P0171: System Too Lean (Bank 1); DTC P0172: System Too Rich (Bank 1) [08/2013 - 08/2016]

      Result

      Proceed to
      NEXT

    Result:  1

    NEXT 

    See step  6

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