SFI 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 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, 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.

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 cycle of the waveform for the heated oxygen sensor is long, the oxygen storage capacity is great. There is a direct correlation between the heated oxygen sensor 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 illuminates the MIL and sets the 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

OSC value is less than the standard value under active air-fuel ratio control

(1 trip detection logic)*1

(2 trip detection logic)*2

  • Gas leakage 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 front exhaust pipe assembly (TWC: Rear catalyst)
P0430

OSC value is less than the standard value under active air-fuel ratio control

(1 trip detection logic)*1

(2 trip detection logic)*2

  • Gas leakage 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 front exhaust pipe assembly (TWC: Rear catalyst)

CATALYST LOCATION

B002BCSE02
Text in Illustration
*1

Exhaust Manifold Sub-assembly RH

(TWC: Front Catalyst)

 *2

Exhaust Manifold Sub-assembly LH

(TWC: Front Catalyst)
*3

Air Fuel Ratio Sensor

(Bank 1 Sensor 1)

 *4

Air Fuel Ratio Sensor

(Bank 2 Sensor 1)
*5

Heated Oxygen Sensor

(Bank 1 Sensor 2)

 *6

Heated Oxygen Sensor

(Bank 2 Sensor 2)
*7

Front Exhaust Pipe Assembly

(TWC: Rear Catalyst)

 *8 Tailpipe RH
*9 Tailpipe LH - -

Note


  • When DTC P0420 is output, replace the exhaust manifold sub-assembly RH (*1) and the front exhaust pipe assembly (*7) together when catalyst replacement is necessary. (Excluding air fuel ratio sensor *3 and heated oxygen sensor *5)

  • When DTC P0430 is output, replace the exhaust manifold sub-assembly LH (*2) and the front exhaust pipe assembly (*7) together when catalyst replacement is necessary. (Excluding air fuel ratio sensor *4 and heated oxygen sensor *6)

MONITOR STRATEGY

Required Sensors/Components (Main) Air fuel ratio sensor and heated oxygen sensor
Required Sensors/Components (Related) Intake air temperature sensor, mass air flow meter, crankshaft position sensor and engine coolant temperature sensor
Frequency of Operation Once per driving cycle

TYPICAL ENABLING CONDITIONS

Auxiliary battery voltage 11 V or more
Intake air temperature -10°C (14°F) or more
Engine coolant temperature 75°C (167°F) or more
Atmospheric pressure 76 kPa(abs) [570 mmHg(abs)] or more
Idle Off
Engine speed Less than 3200 rpm
Air fuel ratio sensor Activated
Fuel system status Closed loop
Engine load 5% or more, and less than 80%
Shift position 4th or more
All of the following conditions are met: Conditions 1, 2 and 3
1. Mass air flow 9 (5)* g/sec or more, and less than 50 g/sec
2. Front catalyst temperature (estimated) 530°C (986°F) or more, and less than 770°C (1418°F)
3. Rear catalyst temperature (estimated) 355°C (671°F) or more, and less than 700°C (1292°F)

*: w/ Canister Pump Module

CONFIRMATION DRIVING PATTERN

Tech Tips


  • It is necessary that the response of the heated oxygen sensor is normal in order to confirm DTCs P0420 and P0430. Therefore, perform the driving pattern for the heated oxygen sensor monitor before performing the drive 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.


B002BSKE39

  1. Connect the GTS to the DLC3.

  2. Turn the power switch on (IG).

  3. Turn the GTS on.

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

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

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

  7. Put the engine in inspection mode (maintenance mode) Click here.

  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 idling stable, turn off the A/C and all other electric loads and do not perform any shift operations.

  9. Drive the vehicle at approximately 75 km/h (47 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. With the shift lever in S position, drive the vehicle at 75 km/h (47 mph), and then decelerate the vehicle by releasing the accelerator pedal for 5 seconds or more to perform the fuel-cut [C].

    CAUTION:

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

  11. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [I].

  12. Check if any DTCs are stored.

    Tech Tips

    If the monitor item does not change to Complete, and no DTCs are stored, perform the following procedure.

  13. Turn the power switch off and wait for at least 30 seconds [F].

  14. Turn the power switch on (IG) and turn the GTS on.

  15. 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 [G].

    Tech Tips

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

  16. Drive the vehicle at approximately 75 km/h (47 mph) for 10 minutes or more [H].

    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.

  17. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [I].

  18. Check if any DTCs are stored.

    Tech Tips

    If the monitor item does not change to Complete, and no DTCs are stored, perform the following procedure.

  19. Drive the vehicle at approximately 100 km/h (62 mph) for 10 minutes or more [J].

    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.

  20. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [K].

  21. Check if any DTCs are stored.

    Tech Tips

    If the monitor item does not change to Complete, and no DTCs are stored, extend the driving time.


B002BI1E01

  1. Connect the GTS to the DLC3.

  2. Turn the power switch on (IG).

  3. Turn the GTS on.

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

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

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

  7. Put the engine in inspection mode (maintenance mode) Click here.

  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 idling stable, turn off the A/C and all other electric loads 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 power switch off and wait for at least 30 seconds [C].

  11. Turn the power switch on (IG) and turn the GTS on.

  12. 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 [D].

    Tech Tips

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

  13. 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.

  14. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [F].

  15. Check if any DTCs (pending DTCs) are stored.

    Tech Tips

    If the monitor item does not change to Complete, and no pending DTCs are stored, perform the following procedure.

  16. 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.

  17. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes [H].

  18. Check if any DTCs (pending DTCs) are stored.

    Tech Tips

    If the monitor item does not change to Complete, and no pending DTCs are stored, 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.

B002BK7E56

  1. Connect the GTS to the DLC3 [A].

  2. Turn the power switch on (IG) and turn the GTS on [A].

  3. Put the engine in inspection mode (maintenance mode) Click here [A].

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

    Tech Tips

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

  5. Run the engine at an engine speed of between 1500 rpm and 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, perform step [C] 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 GTS [D].

    Tech Tips


    • If either of the voltage outputs of either 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 for A/F Sensor.

    • 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).

B002BF9E13

CAUTION / NOTICE / HINT

Tech Tips


  • If a malfunction cannot be found when troubleshooting DTC P0420 or P0430, a lean or rich abnormality may be the cause. Perform troubleshooting by following the inspection procedure for P0171 or P0174 (System Too Lean) and P0172 or P0175 (System Too Rich).

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

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

  • 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 P0420 AND/OR P0430)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

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

      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 GTS (CONTROL THE INJECTION VOLUME FOR A/F SENSOR)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Put the engine in inspection mode (maintenance mode) Click here.

    5. Start the engine and warm it up.

    6. Run 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 for A/F Sensor / AFS Voltage B1S1 and O2S B1S2 or AFS Voltage B2S1 and O2S B2S2.

    8. Perform the Active Test operation with the engine idling (press the RIGHT or LEFT button to change the fuel injection volume).

    9. 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 GTS.

      Tech Tips


      • Change the fuel injection volume within the range of - 12.5% to +12.5%. 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

      GTS Display

      (Sensor)

      		 Injection Volume Status Voltage

      AFS Voltage B1S1 or AFS Voltage B2S1

      (Air fuel ratio)

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

      O2S B1S2 or O2S B2S2

      (Heated oxygen)

      		 +12.5% Rich Higher than 0.55 V
      -12.5% Lean Below 0.4 V
      Result

      Status

      AFS Voltage B1S1

      or

      AFS Voltage B2S1

      Status

      O2S B1S2

      or

      O2S B2S2

      A/F Condition and A/F and

      HO2 Sensor Conditions

      		 Misfire Main Suspected Trouble Areas Proceed to
      Lean/Rich Lean/Rich Normal -

      • Three-Way Catalytic Converter (TWC)

      • Gas leakage 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 May occur

      • Air fuel ratio sensor
      Lean/Rich Lean Heated oxygen sensor malfunction -

      • Heated oxygen sensor

      • Gas leakage from exhaust system

      		 C
      Lean/Rich Rich Heated oxygen sensor malfunction -

      • Heated oxygen 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

      		 D
      Rich Rich Actual air-fuel ratio lean -

      • Extremely rich or lean actual air-fuel ratio

      • Gas leakage from exhaust system

      Lean: During Control the Injection Volume for A/F Sensor, 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 for A/F Sensor, 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 for A/F Sensor of the Active Test, the output voltage of the air fuel ratio sensor and heated oxygen sensor alternate correctly.


    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. Check for exhaust gas leaks.

      OK
      No gas leaks.

      Tech Tips

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


    NG

    REPAIR OR REPLACE EXHAUST GAS LEAK POINT Click here

    OK

  4. CHECK DTC OUTPUT (DTC P0420 AND/OR P0430)

    Note


    • When DTC P0420 is output, replace the exhaust manifold sub-assembly RH (TWC: Front catalyst) and the front exhaust pipe assembly (TWC: Rear catalyst) together when catalyst replacement is necessary.

    • When DTC P0430 is output, replace the exhaust manifold sub-assembly LH (TWC: Front catalyst) and the front 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. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

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

    C

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

    A

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

    B

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

  5. CHECK FOR EXHAUST GAS LEAK


    1. Check for exhaust gas leaks.

      OK
      No gas leaks.

      Tech Tips

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


    OK

    REPLACE HEATED OXYGEN SENSOR Click here

    NG

    REPAIR OR REPLACE EXHAUST GAS LEAK POINT Click here

  6. CHECK FOR EXHAUST GAS LEAK


    1. Check for exhaust gas leaks.

      OK
      No gas leaks.

      Tech Tips

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


    OK

    CHECK CAUSE OF EXTREMELY RICH OR LEARN 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.

      Tech Tips

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


    NEXT

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED Click here

  8. REPAIR OR REPLACE EXHAUST GAS LEAK POINT


    1. Repair or replace exhaust gas leak point.

      Tech Tips

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


    NEXT

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED Click here

  9. REPLACE HEATED OXYGEN SENSOR


    1. Replace the heated oxygen sensor Click here.

      Tech Tips

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


    NEXT

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED Click here

  10. CHECK CAUSE OF EXTREMELY RICH OR LEARN ACTUAL AIR FUEL RATIO


    1. Check the cause of extremely rich or lean actual air fuel ratio, referring to the DTC P0171 Inspection Procedure Click here.


    NEXT

  11. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS 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 GTS on.

    8. Put the engine in inspection mode (maintenance 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 / Trouble Codes.

    12. Read the pending DTCs.

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

    B

    END

    A

  12. CHECK DTC OUTPUT (DTC P0420 AND/OR P0430)

    Note


    • When DTC P0420 is output, replace the exhaust manifold sub-assembly RH (TWC: Front catalyst) and the front exhaust pipe assembly (TWC: Rear catalyst) together when catalyst replacement is necessary.

    • When DTC P0430 is output, replace the exhaust manifold sub-assembly LH (TWC: Front catalyst) and the front 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. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

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

    C

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

    A

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

    B

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