LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2019 >> ES 350 Base >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System (2GR-FKS) - Diagnostic Codes (05 Of 10) >> SFI System >> DTC P0420-00: Catalyst System Efficiency Below Threshold Bank 1; DTC P0430-00: Catalyst System Efficiency Below Threshold Bank 2 [06/2018 - 08/2021] >> Procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

DTC P0420-00: Catalyst System Efficiency Below Threshold Bank 1; DTC P0430-00: Catalyst System Efficiency Below Threshold Bank 2 [06/2018 - 08/2021]: Procedure

  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0420-00 AND/OR P0430-00) 
    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.

      Powertrain > Engine > Trouble Codes 

      Result

      Result Proceed to
      DTC P0420-00 and/or P0430-00 are output A
      DTC P0420-00 and/or P0430-00 and other DTCs are output B

      HINT: 

      If any DTCs other than P0420-00 and/or P0430-00 are output, troubleshoot those DTCs first.

    Result: 

    B 

    GO TO DTC CHART. Refer to  DIAGNOSTIC TROUBLE CODE CHART [06/2018 - 07/2019]  , or refer to  DIAGNOSTIC TROUBLE CODE CHART [07/2019 - 08/2020]  , or refer to  DIAGNOSTIC TROUBLE CODE CHART [08/2020 - 08/2021] 

    Result: 

    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 until the engine coolant temperature is 75°C (167°F) or higher.
    3. Turn the Techstream on.
    4. Warm up the air fuel ratio sensor at an engine speed of 2500 rpm for approximately 90 seconds.
    5. Enter the following menus: Powertrain / Engine / Active Test / Control the Injection Volume for A/F Sensor / Data List / Coolant Temperature, A/F (O2) Sensor Voltage B1S1 and O2 Sensor Voltage B1S2 or A/F (O2) Sensor Voltage B2S1 and O2 Sensor Voltage B2S2.

      Powertrain > Engine > Active Test 

      Active Test Display
      Control the Injection Volume for A/F Sensor
      Data List Display
      Coolant Temperature
      A/F (O2) Sensor Voltage B1S1
      A/F (O2) Sensor Voltage B2S1
      O2 Sensor Voltage B1S2
      O2 Sensor Voltage B2S2
    6. Perform the Active Test operation with the engine idling (change the fuel injection volume).
    7. Monitor the voltage outputs of the air fuel ratio sensor and heated oxygen sensor (A/F (O2) Sensor Voltage B1S1 and O2 Sensor Voltage B1S2 or A/F (O2) Sensor Voltage B2S1 and O2 Sensor Voltage B2S2) 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
      A/F (O2) Sensor Voltage B1S1
      A/F (O2) Sensor Voltage B2S1
      (Air fuel ratio)      		 12.5% Rich Below 3.1 V
      -12.5% Lean Higher than 3.4 V
      O2 Sensor Voltage B1S2
      O2 Sensor Voltage B2S2
      (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 or A/F (O2) Sensor Voltage B2S1 Status of O2 Sensor Voltage B1S2 or O2 Sensor Voltage 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
      1. Lean: During Control the Injection Volume for A/F Sensor, the air fuel ratio sensor output voltage (A/F (O2) Sensor Voltage B1S1 or A/F (O2) Sensor Voltage B2S1) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2 Sensor Voltage B1S2 or O2 Sensor Voltage B2S2) is consistently less than 0.4 V.
      2. Rich: During Control the Injection Volume for A/F Sensor, the A/F (O2) Sensor Voltage B1S1 or A/F (O2) Sensor Voltage B2S1 is consistently less than 3.1 V, and the O2 Sensor Voltage B1S2 or O2 Sensor Voltage B2S2 is consistently higher than 0.55 V.
      3. 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.

    Result: 

    B 

    See step  4

    Result: 

    C 

    See step  5

    Result: 

    D 

    See step  7

    Result: 

    A 

    See step  3

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

      OK

      No gas leaks in exhaust system.

      Result

      Proceed to
      OK
      NG

    Result: 

    OK 

    See step  10

    Result: 

    NG 

    See step  9

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

      Refer to REMOVAL [06/2018 - ]

      HINT: 

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

      Refer to INITIALIZATION [06/2018 - 07/2019] , or refer to INITIALIZATION [07/2019 - ]

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  10

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

      OK

      No gas leaks in exhaust system.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  9

    Result: 

    OK 

    See step  6

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

      Refer to REMOVAL [06/2018 - ]

      HINT: 

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

      Refer to INITIALIZATION [06/2018 - 07/2019] , or refer to INITIALIZATION [07/2019 - ]

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  10

  7. CHECK FOR EXHAUST GAS LEAK 
    1. Check the exhaust gas leaks.

      OK

      No gas leaks in exhaust system.

      Result

      Proceed to
      OK
      NG

    Result: 

    NG 

    See step  9

    Result: 

    OK 

    See step  8

  8. 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 P0171-00 Inspection Procedure.

      Refer to DTC P0171-00: System Too Lean Bank 1; DTC P0172-00: System Too Rich Bank 1; DTC P0174-00: System Too Lean Bank 2; DTC P0175-00: System Too Rich Bank 2; DTC P1170-00: Fuel Performance/Port Injector; DTC P117B-00: Fuel Performance/Direct Injector [06/2018 - 08/2021]

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  10

  9. REPAIR OR REPLACE EXHAUST SYSTEM 
    1. Repair or replace exhaust system.

      HINT: 

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

      Refer to INITIALIZATION [06/2018 - 07/2019] , or refer to INITIALIZATION [07/2019 - ]

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  10

  10. CLEAR DTC 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream on.
    4. Clear the DTC.

      Powertrain > Engine > Clear DTCs 

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

      Result

      Proceed to
      NEXT

    Result: 

    NEXT 

    See step  11

  11. CHECK WHETHER DTC OUTPUT RECURS (DTC P0420-00 AND/OR P0430-00) 
    1. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.
    2. Enter the following menus: Powertrain / Engine / Trouble Codes.
    3. Read the DTCs.

      Powertrain > Engine > Trouble Codes 

      Result

      Result Proceed to
      DTCs are not output
      (No pending DTCs output)      		 A
      DTC P0420-00 and/or P0430-00 are output B

    Result: 

    A 

    END 

    Result: 

    B 

    See step  12

  12. CHECK DTC OUTPUT (DTC P0420-00 AND/OR P0430-00) 
    NOTE:
    • If DTC P0420-00 is output, replace the exhaust manifold (TWC: Front catalyst) and the front exhaust pipe assembly (TWC: Rear catalyst) together when catalyst replacement is necessary.
    • If DTC P0430-00 is output, replace the exhaust manifold assembly LH (TWC: Front catalyst) and the front exhaust pipe assembly (TWC: Rear catalyst) together when catalyst replacement is necessary.

    HINT: 

    Confirm the replacement parts, referring to the illustration in 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.

      Powertrain > Engine > Trouble Codes 

      Result

      Result Proceed to
      DTC P0420-00 is output A
      DTC P0430-00 is output B
      DTC P0420-00 and P0430-00 are output C

    Result: 

    A 

    REPLACE EXHAUST MANIFOLD (TWC: FRONT CATALYST) AND FRONT EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST) 

    Refer to COMPONENTS [06/2018 - ]

    Refer to COMPONENTS [06/2018 - ]

    Result: 

    B 

    REPLACE EXHAUST MANIFOLD ASSEMBLY LH (TWC: FRONT CATALYST) AND FRONT EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST) 

    Refer to COMPONENTS [06/2018 - ]

    Refer to COMPONENTS [06/2018 - ]

    Result: 

    C 

    REPLACE EXHAUST MANIFOLD (TWC: FRONT CATALYST), EXHAUST MANIFOLD ASSEMBLY LH (TWC: FRONT CATALYST) AND FRONT EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST) 

    Refer to COMPONENTS [06/2018 - ]

    Refer to COMPONENTS [06/2018 - ]

scientia non olet · About LEMON Manuals