SFI SYSTEM(for Rear Air Fuel Ratio Sensor), Diagnostic DTC:P042000

DTC Code DTC Name
P042000 Catalyst System Efficiency Below Threshold Bank 1

MONITOR DESCRIPTION

The ECM uses air fuel ratio sensors mounted in front of and behind the Three-Way Catalytic Converter (TWC) to monitor its efficiency.

The first sensor, the air fuel ratio sensor (sensor 1), sends pre-catalyst information to the ECM. The second sensor, the air fuel ratio sensor (sensor 2), sends post-catalyst information to the ECM.

In order to detect any deterioration in the three-way catalytic converter, the ECM calculates the oxygen storage capacity of the three-way catalytic converter. This calculation is based on the output current of the air fuel ratio sensor (sensor 2) while performing active air fuel ratio control.

The oxygen storage capacity value is an indication of the oxygen storage capacity of the three-way catalytic converter. When the vehicle is being driven with a warm engine, active air fuel ratio control is performed for approximately 30 seconds. When it is performed, the ECM deliberately sets the air fuel ratio to lean or rich levels. If the cycle of the waveform for the air fuel ratio sensor (sensor 2) is long, the oxygen storage capacity is great. There is a direct correlation between the air fuel ratio sensor (sensor 2) and the oxygen storage capacity of the three-way catalytic converter.

The ECM uses the oxygen storage capacity value to determine the state of the three-way catalytic converter. If any deterioration has occurred, the ECM will illuminate the MIL and store a DTC.

This system determines the deterioration of the entire catalyst system (including the front and rear catalysts), by using the oxygen storage capacity value of the front catalyst, that is more sensitive than the rear catalyst, as the representative value. Therefore, be sure to replace the front and rear catalysts together when catalyst replacement is necessary.

DTC No. Detection Item DTC Detection Condition Trouble Area MIL Memory Note
P042000 Catalyst System Efficiency Below Threshold Bank 1 The oxygen storage capacity value is less than the standard value under active air fuel ratio control (2 trip detection logic).

  • Gas leak from exhaust system

  • Air fuel ratio sensor (sensor 1)

  • Air fuel ratio sensor (sensor 2)

  • Exhaust manifold converter sub-assembly (TWC: Front catalyst) and front exhaust pipe assembly*1 or center exhaust pipe assembly*2 (TWC: Rear catalyst)

 Comes on DTC stored

SAE Code:

P0420

CATALYST LOCATION

B007WNCC01
*A w/ Canister Pump Module *B w/o Canister Pump Module
*1 Air Fuel Ratio Sensor (Sensor 1) *2 Air Fuel Ratio Sensor (Sensor 2)
*3 Exhaust Manifold Converter Sub-assembly *4 Front Exhaust Pipe Assembly
*5 Center Exhaust Pipe Assembly *6 Tail Exhaust Pipe Assembly
*7 TWC: Front Catalyst *8 TWC: Rear Catalyst

Note


  • w/ Canister Pump Module:

    Replace the exhaust manifold converter sub-assembly (*3) and the front exhaust pipe assembly (*4) together when catalyst replacement is necessary. (Excluding air fuel ratio sensor (sensor 1)*1 and air fuel ratio sensor (sensor 2)*2)

  • w/o Canister Pump Module:

    Replace the exhaust manifold converter sub-assembly (*3) and the center exhaust pipe assembly (*5) together when catalyst replacement is necessary. (Excluding air fuel ratio sensor (sensor 1)*1 and air fuel ratio sensor (sensor 2)*2)

MONITOR STRATEGY

Required Sensors/Components (Main)

Air fuel ratio sensor (sensor 1)

Air fuel ratio sensor (sensor 2)
Required Sensors/Components (Related)

Intake air temperature sensor (mass air flow meter sub-assembly)

Mass air flow meter sub-assembly

Crankshaft position sensor

Engine coolant temperature sensor
Frequency of Operation Once per driving cycle

TYPICAL ENABLING CONDITIONS

Battery voltage 11 V or higher
Intake air temperature -10°C (14°F) or higher
Engine coolant temperature 75°C (167°F) or higher
Atmospheric pressure 76 kPa(abs) [11.02 psi(abs)] or higher
Idling Off
Engine speed Less than 3200 rpm
Air fuel ratio sensor (sensor 1) status Activated
Fuel system status Closed loop
Engine load 10% or higher, and less than 140%
All of the following conditions are met -
Mass air flow rate 3.0 to 50 gm/sec.
Front catalyst temperature (estimated) 500°C (932°F) to 800°C (1472°F)
Rear catalyst temperature (estimated) 370°C (698°F) to 700°C (1292°F)

CONFIRMATION DRIVING PATTERN

Tech Tips


  • It is necessary for the response of the air fuel ratio sensor (sensor 2) to be normal in order to confirm DTC P042000. Therefore, perform the confirmation driving pattern for the air fuel ratio sensor (sensor 2) monitor before performing the confirmation driving pattern for the catalyst efficiency monitor.

  • Performing this confirmation driving pattern will activate the catalyst efficiency monitor. This is very useful for verifying the completion of a repair.

B007YPAE36

  1. Connect the GTS to the DLC3.

  2. Turn the engine switch on (IG).

  3. Turn the GTS on.

  4. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).

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

  6. Turn the engine switch on (IG).

  7. Turn the GTS on.

  8. Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher with the shift lever in P [A].

    Tech Tips

    In order to keep the idle stable, turn the A/C and all other electric loads off and do not perform any shift operations.

  9. Drive the vehicle at approximately 60 km/h (37 mph) for 10 minutes or more [B].

    CAUTION:

    When performing the confirmation driving pattern, obey all speed limits and traffic laws.

    Tech Tips

    Drive the vehicle while keeping the engine load as constant as possible.

  10. Turn the engine switch off and wait for at least 30 seconds [C].

  11. Turn the engine switch on (IG).

  12. Turn the GTS on.

  13. Start the engine and warm it up until the engine coolant temperature is 75°C (167°F) or higher [D].

  14. Drive the vehicle at approximately 60 km/h (37 mph) for 10 minutes or more [E].

    CAUTION:

    When performing the confirmation driving pattern, obey all speed limits and traffic laws.

    Tech Tips

    Drive the vehicle while keeping the engine load as constant as possible.

  15. Enter the following menus: Powertrain / Engine / Trouble Codes [F].

  16. Read the pending DTCs.

    Tech Tips


    • If a pending DTC is output, the system is malfunctioning.

    • If a pending DTC is not output, perform the following procedure.

  17. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

  18. Input the DTC: P042000.

  19. Check the DTC judgment result.

    GTS Display Description
    NORMAL

    • DTC judgment completed

    • System normal
    ABNORMAL

    • DTC judgment completed

    • System abnormal
    INCOMPLETE

    • DTC judgment not completed

    • Perform driving pattern after confirming DTC enabling conditions

    Tech Tips


    • If the judgment result shows NORMAL, the system is normal.

    • If the judgment result shows ABNORMAL, the system has a malfunction.

    • If the judgment result is INCOMPLETE, perform the following procedure.

  20. Drive the vehicle at a speed between 75 and 100 km/h (47 and 62 mph) for 10 minutes or more [G].

    CAUTION:

    When performing the confirmation driving pattern, obey all speed limits and traffic laws.

    Tech Tips

    Drive the vehicle while keeping the engine load as constant as possible.

  21. Enter the following menus: Powertrain / Engine / Trouble Codes [H].

  22. Read the pending DTCs.

    Tech Tips


    • If a pending DTC is output, the system is malfunctioning.

    • If a pending DTC is not output, perform the following procedure.

  23. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

  24. Input the DTC: P042000.

  25. Check the DTC judgment result.

    GTS Display Description
    NORMAL

    • DTC judgment completed

    • System normal
    ABNORMAL

    • DTC judgment completed

    • System abnormal
    INCOMPLETE

    • DTC judgment not completed

    • Perform driving pattern after confirming DTC enabling conditions

    Tech Tips


    • If the judgment result shows NORMAL, the system is normal.

    • If the judgment result shows ABNORMAL, the system has a malfunction.

CAUTION / NOTICE / HINT

Tech Tips


  • If a malfunction cannot be found when troubleshooting DTC P042000, a lean or rich abnormality may be the cause. Perform troubleshooting by following the inspection procedure for P017100 (System Too Lean) and P017200 (System Too Rich).

  • Sensor 1 refers to the sensor closest to the engine assembly.

  • Sensor 2 refers to the sensor farthest away from the engine assembly.

  • Read Freeze Frame Data using the GTS. The ECM records vehicle and driving condition information as Freeze Frame Data the moment a DTC is stored. 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.

PROCEDURE


  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P042000)


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine / Trouble Codes.

    5. Read the DTCs.


      Powertrain > Engine > Trouble Codes
      Result
      Result Proceed to
      DTC P042000 is output A
      DTC P042000 and other DTCs are output B

      Tech Tips

      If any DTCs other than P042000 are output, troubleshoot those DTCs first.


    B

    GO TO DTC CHART Click here

    A

  2. PERFORM ACTIVE TEST USING GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

    5. Warm up the air fuel ratio sensors at an engine speed of 2500 rpm for 90 seconds.

    6. 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 A/F (O2) Sensor Current B1S2.


      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 Current B1S2

    7. Perform the Control the Injection Volume for A/F Sensor operation with the engine idling.

    8. Monitor the output values of the air fuel ratio sensors (A/F (O2) Sensor Voltage B1S1 and A/F (O2) Sensor Current B1S2) displayed on the GTS.

      Tech Tips


      • 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%.

      • The air fuel ratio sensor (sensor 1) has an output delay of a few seconds and the air fuel ratio sensor (sensor 2) has a maximum output delay of approximately 20 seconds.

      • If the sensor output value does not change (almost no reaction) while performing the Active Test, the sensor may be malfunctioning.

      Standard
      GTS Display (Sensor) Injection Volume Status Value

      A/F (O2) Sensor Voltage B1S1

      (Air fuel ratio sensor (sensor 1))

      		 12.5% Rich Below 3.1 V
      -12.5% Lean Higher than 3.4 V

      A/F (O2) Sensor Current B1S2

      (Air fuel ratio sensor (sensor 2))

      		 12.5% Rich Below -0.86 mA
      -12.5% Lean More than 0.33 mA
      Result
      Status of A/F (O2) Sensor Voltage B1S1 Status of A/F (O2) Sensor Current B1S2 Air Fuel Ratio Condition and Air Fuel Ratio Sensors Condition 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 (sensor 1) malfunction

      • Air fuel ratio sensor (sensor 1)

      		 B
      Rich Lean/Rich Air fuel ratio sensor (sensor 1) malfunction

      • Air fuel ratio sensor (sensor 1)
      Lean/Rich Lean Air fuel ratio sensor (sensor 2) malfunction

      • Air fuel ratio sensor (sensor 2)

      • Gas leak from exhaust system

      		 C
      Lean/Rich Rich Air fuel ratio sensor (sensor 2) malfunction

      • Air fuel ratio sensor (sensor 2)

      • Gas leak from exhaust system
      Lean Lean Actual air fuel ratio lean

      • 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 the Control the Injection Volume for A/F Sensor Active Test, the air fuel ratio sensor (sensor 1) output voltage (A/F (O2) Sensor Voltage B1S1) is consistently higher than 3.4 V, and the air fuel ratio sensor (sensor 2) output current (A/F (O2) Sensor Current B1S2) is consistently more than 0.33 mA.

      • Rich: During the Control the Injection Volume for A/F Sensor Active Test, the air fuel ratio sensor (sensor 1) output voltage (A/F (O2) Sensor Voltage B1S1) is consistently below 3.1 V, and the air fuel ratio sensor (sensor 2) output current (A/F (O2) Sensor Current B1S2) is consistently below -0.86 mA.

      • Lean/Rich: During the Control the Injection Volume for A/F Sensor Active Test, the output value of the air fuel ratio sensor (sensor 1) or air fuel ratio sensor (sensor 2) alternate correctly.

      Tech Tips

      Refer to "Data List / Active Test" [A/F (O2) Sensor Voltage B1S1, A/F (O2) Sensor Current B1S2].

      Click here


    B

    REPLACE AIR FUEL RATIO SENSOR (SENSOR 1) Click here

    C

    CHECK FOR EXHAUST GAS LEAK Click here

    D

    CHECK FOR EXHAUST GAS LEAK Click here

    A

  3. CHECK FOR EXHAUST GAS LEAK


    1. Check for exhaust gas leaks.

      OK
      No gas leaks in exhaust system.
      Result
      Result Proceed to
      OK (w/ Canister Pump Module) A
      OK (w/o Canister Pump Module) B
      NG C

    A

    GO TO STEP 12 Click here

    B

    GO TO STEP 13 Click here

    C

    GO TO STEP 9 Click here

  4. REPLACE AIR FUEL RATIO SENSOR (SENSOR 1)


    1. Replace the air fuel ratio sensor (sensor 1).

      Click here

      Tech Tips

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

      Click here

      Result
      Proceed to
      NEXT

    NEXT

    GO TO STEP 11 Click here

  5. CHECK FOR EXHAUST GAS LEAK


    1. Check for exhaust gas leaks.

      OK
      No gas leaks in exhaust system.
      Result
      Proceed to
      OK
      NG

    NG

    GO TO STEP 9 Click here

    OK

  6. REPLACE AIR FUEL RATIO SENSOR (SENSOR 2)


    1. Replace the air fuel ratio sensor (sensor 2).

      Click here

      Tech Tips

      Perform "Inspection After Repair" after replacing the air fuel ratio sensor (sensor 2).

      Click here

      Result
      Proceed to
      NEXT

    NEXT

    GO TO STEP 11 Click here

  7. CHECK FOR EXHAUST GAS LEAK


    1. Check for exhaust gas leaks.

      OK
      No gas leaks in exhaust system.
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE EXHAUST SYSTEM Click here

    OK

  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 P017100 and P017200 Inspection Procedure.

      Click here

      Result
      Proceed to
      NEXT

    NEXT

    GO TO STEP 11 Click here

  9. REPAIR OR REPLACE EXHAUST SYSTEM


    1. Repair or replace exhaust system.

      Tech Tips

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

      Click here

      Result
      Proceed to
      NEXT

    NEXT

  10. CLEAR DTC


    1. Connect the GTS to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the GTS on.

    4. Clear the DTCs.


      Powertrain > Engine > Clear DTCs

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

      Result
      Proceed to
      NEXT

    NEXT

  11. CHECK WHETHER DTC OUTPUT RECURS (DTC P042000)


    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 A
      DTC P042000 is output (w/ Canister Pump Module) B
      DTC P042000 is output (w/o Canister Pump Module) C

    A

    END

    C

    REPLACE EXHAUST MANIFOLD CONVERTER SUB-ASSEMBLY (TWC: FRONT CATALYST) AND CENTER EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST) Click here

    B

  12. REPLACE EXHAUST MANIFOLD CONVERTER SUB-ASSEMBLY (TWC: FRONT CATALYST) AND FRONT EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST)

    Note

    When replacing the exhaust manifold converter sub-assembly and the front exhaust pipe assembly in order to replace the three-way catalytic converter, it is not necessary to replace the air fuel ratio sensor (sensor 1) and the air fuel ratio sensor (sensor 2).

    Tech Tips

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


    1. Replace the exhaust manifold converter sub-assembly (TWC: Front catalyst).

      Click here

    2. Replace the front exhaust pipe assembly (TWC: Rear catalyst).

      Click here

      Result
      Proceed to
      NEXT

    NEXT

    END

  13. REPLACE EXHAUST MANIFOLD CONVERTER SUB-ASSEMBLY (TWC: FRONT CATALYST) AND CENTER EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST)

    Note

    When replacing the exhaust manifold converter sub-assembly and the center exhaust pipe assembly in order to replace the three-way catalytic converter, it is not necessary to replace the air fuel ratio sensor (sensor 1) and the air fuel ratio sensor (sensor 2).

    Tech Tips

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


    1. Replace the exhaust manifold converter sub-assembly (TWC: Front catalyst).

      Click here

    2. Replace the center exhaust pipe assembly (TWC: Rear catalyst).

      Click here

      Result
      Proceed to
      NEXT

    NEXT

    END