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Home >> Lexus >> 2009 >> LS 460 AWD >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - Diagnostic Codes (2 Of 4) >> DTC P0420 Catalyst System Efficiency Below Threshold (Bank1); DTC P0430 Catalyst System Efficiency Below Threshold (Bank 2) >> Inspection Procedure

Inspection Procedure

HINT:

Malfunctioning areas can be identified by performing the Control the Injection Volume for A/F sensor function provided in the Active Test. The Control the Injection Volume for A/F sensor function can help to determine whether the Air-Fuel Ratio (A/F) sensor, Heated Oxygen (HO2) sensor and other potential trouble areas are malfunctioning.

The following instructions describe how to conduct the Control the Injection Volume for A/F sensor operation using the Techstream.

  1. Connect the Techstream to the DLC3.
  2. Start the engine and turn the Techstream ON.
  3. Warm up the engine at an engine speed of 2500 RPM for approximately 90 seconds.
  4. On the Techstream, enter the following menus: Powertrain/Engine/Active Test/Control the Injection Volume for A/F sensor.
  5. Perform the Active Test operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume.)
  6. Monitor the output voltages of the A/F and HO2 sensors (AFS Voltage B1 S1 and O2S B1 S2 or AFS Voltage B2 S1 and O2S B2 S2) displayed on the Techstream.

HINT:

INJECTION VOLUME REFERENCE

Tester Display (Sensor) Injection Volume Status Voltage
AFS Voltage B1 S1 or AFS Voltage B2 S1 (A/F) +25% Rich Less than 3.1 V
AFS Voltage B1 S1 or AFS Voltage B2 S1 (A/F) -12.5% Lean More than 3.4 V
O2S B1 S2 or O2S B2 S2 (HO2) +25% Rich More than 0.55 V
O2S B1 S2 or O2S B2 S2 (HO2) -12.5% Lean Less than 0.4 V
NOTE: The Air-Fuel Ratio (A/F) sensor has an output delay of a few seconds and the Heated Oxygen (HO2) sensor has a maximum output delay of approximately 20 seconds.
A/F SENSOR (SENSOR 1) VOLTAGE OUTPUT REFERENCE

Case A/F Sensor (Sensor 1) Output Voltage HO2 Sensor (Sensor 2) Output Voltage Main Suspected Trouble Area
1
G06189918Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
G06189919Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
 -
2
G06189920Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
G06189921Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  • A/F sensor
  • A/F sensor heater
  • A/F sensor circuit
3
G06189922Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
G06189923Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  • HO2 sensor
  • HO2 sensor heater
  • HO2 sensor circuit
4
G06189924Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
G06189925Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  • Injector
  • Fuel pressure
  • Gas leakage from exhaust system (Air-fuel ratio extremely rich or lean)

HINT:

Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. 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.

  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) and turn the Techstream ON.
    3. Enter the following menus: Powertrain/Engine/Trouble Codes.
    4. Read DTCs.

    Result 

    RESULT REFERENCE

    Display (DTC Output) Proceed to
    P0420 and/or P0430 A
    P0420 and/or P0430 and other DTCs B

    HINT:

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

    B: GO TO DTC CHART  (See DIAGNOSTIC TROUBLE CODE CHART )

    A: Go to next step 

  2. PERFORM ACTIVE TEST USING TECHSTREAM 
    1. Connect the Techstream to the DLC3.
    2. Start the engine and turn the Techstream ON.
    3. Warm up the engine at an engine speed of 2500 RPM for approximately 90 seconds.
    4. Enter the following menus: Powertrain/Engine/Active Test/Control the Injection Volume for A/F sensor.
    5. Perform the Control the Injection Volume for A/F sensor operation with the engine in an idling condition (press the RIGHT or LEFT button to change the fuel injection volume).
    6. Monitor the voltage outputs of the A/F and HO2 sensors (AFS Voltage B1 S1 and O2S B1 S2 or AFS Voltage B2 S1 and O2S B2 S2) 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 25%.
      • Each sensor reacts in accordance with increases and decreases in the fuel injection volume.

      Standard 

      INJECTION VOLUME REFERENCE

      Tester Display (Sensor) Injection Volume Status Voltage
      AFS Voltage B1 S1 or AFS Voltage B2 S1 (A/F) +25% Rich Less than 3.1
      AFS Voltage B1 S1 or AFS Voltage B2 S1 (A/F) -12.5% Lean More than 3.4
      O2S B1 S2 or O2S B2 S2 (HO2) +25% Rich More than 0.55
      O2S B1 S2 or O2S B2 S2 (HO2) -12.5% Lean Less than 0.4

      Result 

      RESULT REFERENCE

      Status AFS Voltage B1 S1 or AFS Voltage B2 S1 Status O2S B1 S2 or O2S B2 S2 A/F Condition and A/F and HO2 Sensors Conditions Misfires Main Suspected Trouble Area Proceed to
      Lean/Rich Lean/Rich Normal -
      • Three-Way Catalytic Converter (TWC)
      • Gas leakage from exhaust system
      		 A
      Lean Lean/Rich A/F sensor malfunction -
      • A/F sensor
      		 B
      Rich Lean/Rich A/F sensor malfunction -
      • A/F sensor
      Lean/Rich Lean HO2 sensor malfunction -
      • HO2 sensor
      • Gas leakage from exhaust system
      		 C
      Lean/Rich Rich HO2 sensor malfunction -
      • HO2 sensor
      • Gas leakage from exhaust system
      Lean Lean Actual air-fuel ratio lean May occur
      • Extremely rich or lean actual air-fuel ratio
      • Gas leakage from exhaust system
      		 A
      Rich Rich Actual air-fuel ratio rich -
      • Extremely rich or lean actual air-fuel ratio
      • Gas leakage from exhaust system

      Lean: During Control the Injection Volume for A/F sensor, the A/F sensor output voltage (AFS) is consistently more than 3.4 V, and the HO2 sensor output voltage (O2S) is consistently less than 0.4 V. Rich: During Control the Injection Volume for A/F sensor, the AFS is consistently less than 3.1 V, and the O2S is consistently more than 0.55 V.

      Lean/Rich: During Control the Injection Volume for A/F sensor of the Active Test, the output voltage of the HO2 sensor alternates correctly.

    B: CHECK AND REPLACE AIR FUEL RATIO SENSOR  (See REMOVAL )

    C: CHECK AND REPLACE HEATED OXYGEN SENSOR, AND CHECK AND REPAIR EXHAUST GAS LEAKAGE  (See REMOVAL )

    A: Go to next step 

  3. CHECK FOR EXHAUST GAS LEAK 

    OK: 

    No gas leakage. 

    NG: REPAIR OR REPLACE EXHAUST GAS LEAKAGE POINT 

    OK: Go to next step 

  4. CHECK DTC OUTPUT (DTC P0420 AND/OR P0430) 
    1. According to the output DTCs in the step 1 (Check Any Other DTCs Output), proceed to next step referring to the table below.

    Result 

    RESULT REFERENCE

    Display (DTC output) Proceed to
    P0420 A
    P0430 B
    P0420 and P0430 A and B

    B:  Go to step  6

    A: Go to next step 

  5. REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY LH 
    1. Replace exhaust manifold sub-assembly LH (See REMOVAL ).

    NEXT: REPLACE FRONT EXHAUST PIPE ASSEMBLY  (See REMOVAL )

  6. REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY RH 
    1. Replace exhaust manifold sub-assembly RH (See REMOVAL ).

    NEXT: REPLACE FRONT EXHAUST PIPE ASSEMBLY  (See REMOVAL )

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