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Home >> Lexus >> 2013 >> RX 350 Base, FWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (Diagnostic Codes (P0136 - P0504)) >> SFI System >> DTC P0420: Catalyst System Efficiency Below Threshold (Bank 1); DTC P0430: Catalyst System Efficiency Below Threshold (Bank 2) (07/2012 -) >> Procedure
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DTC P0420: Catalyst System Efficiency Below Threshold (Bank 1); DTC P0430: Catalyst System Efficiency Below Threshold (Bank 2) (07/2012 -): Procedure

  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420 AND/OR P0430) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Trouble Codes.
    5. Read the DTCs.

      Result

      Result Proceed to
      DTC P0420 and/or P0430 are output A
      DTC P0420 and/or P0430 and other DTCs are output B

      HINT: 

      If any DTCs other than P0420 or P0430 are output, troubleshoot those DTCs first.

    B → See step   13 

    A: Go to next step 

  2. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE INJECTION VOLUME) 
    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 / Active Test / Control the Injection Volume / AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2.
    6. Perform the Active Test operation with the engine idling (press the RIGHT or LEFT 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 or AFS Voltage B2S1 and O2S B2S2) displayed on the Techstream.

      HINT: 

      • Change the fuel injection volume within the range of - 12% to +12%. The injection volume can be changed in fine gradations.
      • 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 or AFS Voltage B2S1
      (Air fuel ratio)      		 +12% Rich Below 3.1 V
      -12% Lean Higher than 3.4 V
      O2S B1S2 or O2S B2S2
      (Heated oxygen)      		 +12% Rich Higher than 0.55 V
      -12% Lean Below 0.4 V
      RESULT

      Status
      AFS Voltage B1S1 or AFS Voltage B2S1      		 Status
      O2S B1S2 or O2S B2S2      		 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, the air fuel ratio sensor output voltage (AFS Voltage B1S1 or AFS Voltage B2S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S B1S2 or O2S B2S2) is consistently below 0.4 V.
      • Rich: During Control the Injection Volume, the AFS Voltage B1S1 or AFS Voltage B2S1 is consistently below 3.1 V, and the O2S B1S2 or O2S B2S2 is consistently higher than 0.55 V.
      • Lean/Rich: During Control the Injection Volume of the Active Test, the output voltage of the air fuel ratio sensor and heated oxygen sensor alternate correctly.

    B → See step   7 

    C → See step   5 

    D → See step   6 

    A: Go to next step 

  3. CHECK FOR EXHAUST GAS LEAK 
    1. Inspect for exhaust gas leaks from the exhaust manifold sub-assembly and exhaust pipes.

      OK

      No gas leaks.

    NG → See step   8 

    OK: Go to next step 

  4. CHECK DTC OUTPUT (DTC P0420 AND/OR P0430) 
    NOTE:
    • When outputting DTC P0420 replace the exhaust manifold sub-assembly RH (TWC: Front catalyst) and the center exhaust pipe assembly (TWC: Rear catalyst) together when catalysts replacement is necessary.
    • When outputting DTC P0430 replace the exhaust manifold sub-assembly LH (TWC: Front catalyst) and the center exhaust pipe assembly (TWC: Rear catalyst) together when catalysts replacement is necessary.

    HINT: 

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

    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Trouble Codes.
    5. Read the DTCs.
      RESULT

      Result Proceed to
      DTC P0420 is output A, C
      DTC P0430 is output B, C
      DTC P0420 and P0430 are output A, B, C

    A → See step   14 

    B → See step   15 

    C → See step   16 

  5. CHECK FOR EXHAUST GAS LEAK 
    1. Inspect for exhaust gas leaks from the exhaust manifold sub-assembly and exhaust pipes.

      OK

      No gas leaks.

    OK → See step   9 

    NG → See step   8 

  6. CHECK FOR EXHAUST GAS LEAK 
    1. Inspect for exhaust gas leaks from the exhaust manifold sub-assembly and exhaust pipes.

      OK

      No gas leaks.

    OK → See step   10 

    NG → See step   8 

  7. REPLACE AIR FUEL RATIO SENSOR 
    1. Replace the air fuel ratio sensor. Refer to REMOVAL [03/2012 - ] .

    NEXT → See step   11 

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

    NEXT → See step   11 

  9. REPLACE HEATED OXYGEN SENSOR 
    1. Replace the heated oxygen sensor. Refer to REMOVAL [03/2012 - ] .

    NEXT → See step   11 

  10. 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 P0174 Inspection Procedure. Refer to INSPECTION PROCEDURE .

    NEXT: Go to next step 

  11. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Clear the DTCs. Refer to DTC CHECK / CLEAR [07/2012 - ] .
    5. Turn the engine switch off and wait for at least 30 seconds.
    6. Start the engine.
    7. Turn the Techstream on.
    8. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    9. Enter the following menus: Powertrain / Engine / Trouble Codes.
    10. Read the pending DTCs.
      RESULT

      Result Proceed to
      DTC P0420 and/or P0430 is output A
      DTC is not output B

    B → END 

    A: Go to next step 

  12. CHECK DTC OUTPUT (DTC P0420 AND/OR P0430) 
    NOTE:
    • When outputting DTC P0420 replace the exhaust manifold sub-assembly RH (TWC: Front catalyst) and the center exhaust pipe assembly (TWC: Rear catalyst) together when catalysts replacement is necessary.
    • When outputting DTC P0430 replace the exhaust manifold sub-assembly LH (TWC: Front catalyst) and the center exhaust pipe assembly (TWC: Rear catalyst) together when catalysts replacement is necessary.

    HINT: 

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

    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Enter the following menus: Powertrain / Engine / Trouble Codes.
    5. Read the DTCs.
      RESULT

      Result Proceed to
      DTC P0420 is output A, C
      DTC P0430 is output B, C
      DTC P0420 and P0430 are output A, B, C

    A → See step   14 

    B → See step   15 

    C → See step   16 

  13. GO TO DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [07/2012 - ] 
  14. REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY RH (TWC: FRONT CATALYST). Refer to  COMPONENTS [03/2012 - ] 
  15. REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY LH (TWC: FRONT CATALYST). Refer to  COMPONENTS [03/2012 - ] 
  16. REPLACE CENTER EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST). Refer to  COMPONENTS [03/2012 - ] 
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