SFI SYSTEM (w/o EGR System), Diagnostic DTC:P0420, P0430

DTC Code DTC Name
P0420 Catalyst System Efficiency Below Threshold (Bank 1)
P0430 Catalyst System Efficiency Below Threshold (Bank 2)

DESCRIPTION

The ECM uses the sensors mounted in front of and behind the three-way catalytic converter to monitor its efficiency.

The first sensor, the air fuel ratio sensor, sends pre-catalyst information to the ECM. The second sensor, the heated oxygen sensor, 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 voltage output of the heated oxygen sensor while performing active air fuel ratio control, rather than the conventional detecting method, which uses the locus ratio.

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 15 to 20 seconds. When it is performed, the ECM deliberately sets the air fuel ratio to lean or rich levels. If the rich-lean cycle of the heated oxygen sensor is long, the oxygen storage capacity is large. There is a direct correlation between the oxygen storage capacity of the three-way catalytic converter and the response of the heated oxygen sensor.

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 illuminates the MIL and sets 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. DTC Detection Condition Trouble Area
P0420

Oxygen storage capacity value is less than the standard value under active air fuel ratio control

(2 trip detection logic)

  • Gas leaks from exhaust system

  • Air fuel ratio sensor (bank 1 sensor 1)

  • Heated oxygen sensor (bank 1 sensor 2)

  • Exhaust manifold sub-assembly RH (TWC: Front catalyst) and center exhaust pipe assembly (TWC: Rear catalyst)
P0430

Oxygen storage capacity value is less than the standard value under active air fuel ratio control

(2 trip detection logic)

  • Gas leaks from exhaust system

  • Air fuel ratio sensor (bank 2 sensor 1)

  • Heated oxygen sensor (bank 2 sensor 2)

  • Exhaust manifold sub-assembly LH (TWC: Front catalyst) and center exhaust pipe assembly (TWC: Rear catalyst)

CATALYST LOCATION

A01NESVE01
Text in Illustration
*1

Exhaust Manifold Sub-assembly RH

(TWC: Front Catalyst)

 *2

Exhaust Manifold Sub-assembly LH

(TWC: Front Catalyst)
*3 Front Exhaust Pipe Assembly *4 No. 3 Front Exhaust Pipe Sub-assembly
*5

Center Exhaust Pipe Assembly

(TWC: Rear Catalyst)

 *6 Tail Exhaust Pipe Assembly
*7

Air Fuel Ratio Sensor

(Bank 1 Sensor 1)

 *8

Air Fuel Ratio Sensor

(Bank 2 Sensor 1)
*9

Heated Oxygen Sensor

(Bank 1 Sensor 2)

 *10

Heated Oxygen Sensor

(Bank 2 Sensor 2)
*a w/ Exhaust Heat Recirculation System *b w/o Exhaust Heat Recirculation System

Note


  • When outputting DTC P0420 replace the exhaust manifold sub-assembly RH (*1) and center exhaust pipe assembly (*5) together when catalysts replacement is necessary.

  • When outputting DTC P0430 replace the exhaust manifold sub-assembly LH (*2) and center exhaust pipe assembly (*5) together when catalysts replacement is necessary.

CONFIRMATION DRIVING PATTERN

Tech Tips

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

A01NFBME68

  1. Connect the intelligent tester to the DLC3.

  2. Turn the power switch on (IG).

  3. Turn the tester on.

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

  5. Turn the power switch off and wait for 30 seconds.

  6. Turn the power switch on (IG) and turn the tester on.

  7. Put the engine in inspection mode Click here.

  8. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / Catalyst Monitor.

  9. Check the Catalyst Monitor is Incmol (Incomplete).

  10. Start the engine and warm it up (until the engine coolant temperature is 75°C (167°F) or more) [A].

  11. Drive the vehicle at between 64 km/h and 113 km/h (40 mph and 70 mph) for at least 10 minutes or more [B].

  12. Those items will change to Compl (Complete) after completing the driving pattern.

  13. Enter the following menus: Powertrain / Engine and ECT / DTC / Pending.

  14. Check if any DTCs (pending DTCs) are set.

Tech Tips

If Catalyst does not change to Compl (Complete), and no pending DTCs are set, extend the driving time.

CONDITIONING FOR SENSOR TESTING

Tech Tips

Perform the operation with the engine speeds and time durations described below prior to checking the waveforms of the air fuel ratio and heated oxygen sensors. This is in order to activate the sensors sufficiently to obtain the appropriate inspection results.

A01NFN9E01

  1. Connect the intelligent tester to the DLC3 [A].

  2. Turn the power switch on (IG) and turn the tester on.

  3. Put the engine in inspection mode Click here.

  4. Start the engine and warm it up with all the accessories switched off, until the engine coolant temperature stabilizes [B].

  5. Run the engine at an engine speed of 2500 rpm for at least 3 minutes [C].

    Tech Tips

    During charging control, the engine speed is set at idle. Therefore, the engine speed does not increase when depressing the accelerator pedal. In this case, warm up the engine after charging control has completed.

  6. While running the engine at 2500 rpm and 1500 rpm for 2 seconds, check the waveforms of the air fuel ratio and heated oxygen sensors using the tester [D].

    Tech Tips


    • If either of the voltage outputs of the air fuel ratio or heated oxygen sensor does not fluctuate, or either of the sensors makes a noise, the sensor may be malfunctioning.

    • If the voltage outputs of both the sensors remain lean or rich, the air fuel ratio may be extremely lean or rich. In such cases, enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume.

    • If the three-way catalytic converter has deteriorated, the heated oxygen sensor (located behind the three-way catalytic converter) voltage output fluctuates up and down frequently, even under normal driving conditions (active air fuel ratio control is not performed).

A01NGTFE09

INSPECTION PROCEDURE

Tech Tips


  • After performing repairs, drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern and check if DTC P0420 or P0430 is output again. If a DTC is output again, replace the catalyst if it has not been replaced already.

  • Read freeze frame data using the intelligent tester. 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.

  • Bank 1 refers to the bank that includes the No. 1 cylinder*.

    *: The No. 1 cylinder is the cylinder which is farthest from the transmission.

  • Bank 2 refers to the bank that does not include the No. 1 cylinder.

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

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

PROCEDURE


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


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / DTC.

    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

      Tech Tips

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


    B

    GO TO DTC CHART Click here

    A

  2. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (CONTROL THE INJECTION VOLUME)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the tester on.

    4. Put the engine in inspection mode Click here.

    5. Start the engine.

    6. Warm up the engine at an engine speed of 2500 rpm for approximately 90 seconds.

      Tech Tips

      During charging control, the engine speed is set at idle. Therefore, the engine speed does not increase when depressing the accelerator pedal. In this case, warm up the engine after charging control has completed.

    7. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume.

    8. Perform the Control the Injection Volume operation with the engine in an idling condition.

    9. Monitor the voltage outputs of the air fuel ratio and heated oxygen sensors (AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2) displayed on the tester.

      Tech Tips


      • Change the fuel injection volume within the range of - 12.0% to +12.0%. The injection volume can be changed in fine gradations.

      • 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.

      Tester Display (Sensor) Injection Volume Status Voltage

      AFS Voltage B1S1 or AFS Voltage B2S1

      (Air fuel ratio)

      		 +12% Rich Below 3.1 V

      AFS Voltage B1S1 or AFS Voltage B2S1

      (Air fuel ratio)

      		 -12% Lean Higher than 3.4 V

      O2S B1S2 or O2S B2S2

      (Heated oxygen)

      		 +12% Rich Higher than 0.55 V

      O2S B1S2 or O2S B2S2

      (Heated oxygen)

      		 -12% Lean Below 0.4 V
      Result
      Status of AFS Voltage B1S1 or AFS Voltage B2S1 Status of O2S B1S2 or O2S B2S2 Air Fuel Ratio Condition and Air Fuel Ratio and Heated Oxygen Sensor Condition Misfire Suspected Trouble Area Proceed to
      Lean/Rich Lean/Rich Normal -

      • Three-way catalytic converter

      • Gas leaks 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 B
      Lean/Rich Lean Heated oxygen sensor malfunction -

      • Heated oxygen sensor

      • Gas leaks from exhaust system

      		 C
      Lean/Rich Rich Heated oxygen sensor malfunction -

      • Heated oxygen sensor

      • Gas leaks from exhaust system

      		 C
      Lean Lean Actual air fuel ratio lean May occur

      • Extremely rich or lean actual air fuel ratio

      • Gas leaks from exhaust system

      		 D
      Rich Rich Actual air fuel ratio rich -

      • Extremely rich or lean actual air fuel ratio

      • Gas leaks from exhaust system

      		 D

      Lean: During the Control the Injection Volume Active Test, the air fuel ratio sensor output voltage (AFS Voltage) is consistently higher than 3.4 V, and the heated oxygen sensor output voltage (O2S) is consistently below 0.4 V.

      Rich: During the Control the Injection Volume Active Test, the AFS Voltage is consistently below 3.1 V, and the O2S is consistently higher than 0.55 V.

      Lean/Rich: During the Control the Injection Volume Active Test, the output voltage of the air fuel ratio sensor and heated oxygen sensor alternates correctly.

    10. Refer to "Data List / Active Test" [AFS Voltage B1S1, AFS Voltage B2S1, O2S B1S2 and O2S B2S2] Click here.


    B

    REPLACE AIR FUEL RATIO SENSOR 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. Inspect for exhaust gas leaks from the exhaust manifold sub-assembly and exhaust pipes.

      OK
      No gas leaks.

    NG

    REPAIR OR REPLACE EXHAUST GAS LEAK POINT Click here

    OK

  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 catalyst 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 catalyst replacement is necessary.

    Tech Tips

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


    1. According to the DTCs output in the Check Any Other DTCs Output step, proceed to the next step according to the table below.

      Result
      Display (DTC Output) Proceed to
      DTC P0420 A, C
      DTC P0430 B, C
      DTC P0420 and DTC P0430 A, B, C

    B

    REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY LH (TWC: FRONT CATALYST) Click here

    C

    REPLACE CENTER EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST) Click here

    A

    REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY RH (TWC: FRONT CATALYST) Click here

  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

    REPLACE HEATED OXYGEN SENSOR Click here

    NG

    REPAIR OR REPLACE EXHAUST GAS LEAK POINT Click here

  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

    CHECK CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO Click here

    NG

    REPAIR OR REPLACE EXHAUST GAS LEAK POINT Click here

  7. REPLACE AIR FUEL RATIO SENSOR


    1. Replace the air fuel ratio sensor Click here.


    NEXT

    CHECK DTC OUTPUT (DTC P0420 OR P0430) Click here

  8. REPAIR OR REPLACE EXHAUST GAS LEAK POINT


    1. Repair or replace exhaust gas leak point.


    NEXT

    CHECK DTC OUTPUT (DTC P0420 OR P0430) Click here

  9. REPLACE HEATED OXYGEN SENSOR


    1. Replace the heated oxygen sensor Click here.


    NEXT

    CHECK DTC OUTPUT (DTC P0420 OR P0430) Click here

  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 Click here.


    NEXT

  11. CHECK DTC OUTPUT (DTC P0420 OR P0430)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the tester on.

    4. Clear the DTCs Click here.

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

    6. Turn the power switch on (IG).

    7. Turn the tester on.

    8. Put the engine in inspection mode Click here.

    9. Start the engine.

    10. Drive the vehicle in accordance with the driving pattern described in Confirmation Driving Pattern.

    11. Enter the following menus: Powertrain / Engine and ECT / DTC.

    12. Read the DTCs.

      Result
      Result Proceed to
      DTC P0420 or P0430 is output A

      DTC is not output

      No pending DTCs output)

      		 B

    B

    END

    A

  12. CHECK DTC OUTPUT (DTC P0420 AND/OR O0430)

    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 catalyst 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 catalyst replacement is necessary.

    Tech Tips

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


    1. According to the DTCs output in the Check Any Other DTCs Output step, proceed to the next step according to the table below.

      Result
      Display (DTC Output) Proceed to
      DTC P0420 A, C
      DTC P0430 B, C
      DTC P0420 and DTC P0430 A, B, C

    B

    REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY LH (TWC: FRONT CATALYST) Click here

    C

    REPLACE CENTER EXHAUST PIPE ASSEMBLY (TWC: REAR CATALYST) Click here

    A

    REPLACE EXHAUST MANIFOLD SUB-ASSEMBLY RH (TWC: FRONT CATALYST) Click here