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

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

MONITOR 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 (TWC), the ECM calculates the Oxygen Storage Capacity (OSC) of the Three-way Catalytic Converter (TWC). This calculation is based on the voltage output of the heated oxygen sensor while performing active air-fuel ratio control.

The OSC value is an indication of the oxygen storage capacity of the Three-way Catalytic Converter (TWC). 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 OSC becomes greater. There is a direct correlation between the OSCs of the heated oxygen sensor and Three-way Catalytic Converter (TWC).

The ECM uses the OSC value to determine the state of the Three-way Catalytic Converter (TWC). If any deterioration has occurred, it illuminates the MIL and stores the DTC.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Warning Indicate

Memory

P0420

Catalyst System Efficiency Below Threshold (Bank 1)

OSC 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 (for Bank 1 Sensor 1)

  • Heated oxygen sensor (for Bank 1 Sensor 2)

  • Exhaust manifold assembly LH (TWC: Front catalyst)

  • Front No. 2 exhaust pipe assembly (TWC: Rear catalyst)

  • EGR valve assembly

Comes on

DTC stored

P0430

Catalyst System Efficiency Below Threshold (Bank 2)

OSC 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 (for Bank 2 Sensor 1)

  • Heated oxygen sensor (for Bank 2 Sensor 2)

  • Exhaust manifold assembly RH (TWC: Front catalyst)

  • Front exhaust pipe assembly (TWC: Rear catalyst)

  • EGR valve assembly

Comes on

DTC stored
Tip:

  • DTC P0420 and P0430 are for Euro-OBD only.

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

  • 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.

CATALYST LOCATION

A231712C01

*1

Exhaust Manifold Assembly RH (TWC: Front catalyst)

*2

Exhaust Manifold Assembly LH (TWC: Front catalyst)

*3

Front Exhaust Pipe Assembly (TWC: Rear catalyst)

*4

Front No. 2 Exhaust Pipe Assembly (TWC: Rear catalyst)

*5

Center Exhaust Pipe Assembly

*6

Tailpipe Assembly

*7

Air Fuel Ratio Sensor (for Bank 2 Sensor 1)

*8

Air Fuel Ratio Sensor (for Bank 1 Sensor 1)

*9

Heated Oxygen Sensor (for Bank 2 Sensor 2)

*10

Heated Oxygen Sensor (for Bank 1 Sensor 2)

MONITOR STRATEGY

Required Sensors/Components (Main)

Air fuel ratio sensor and heated oxygen sensor heater

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

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 (570 mmHg) or higher

Idling

OFF

Engine speed

Less than 3200 rpm

Air fuel ratio sensor status

Activated

Fuel system status

Closed loop

Engine load

10 to 75%

All of following conditions (a), (b) and (c) met

-

(a) Mass air flow

7.5 to 75 g/sec.

(b) Estimated front catalyst temperature

650 to 820°C (1202 to 1508°F)

(c) Estimated rear catalyst temperature

400 to 700°C (752 to 1292°F)

Transmission gear

4th or higher
Tip:

The estimated catalyst temperature can be read in the Data List using the intelligent tester.

CONFIRMATION DRIVING PATTERN

Tip:

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

A280865E03

  1. Connect the intelligent tester to the DLC3.

  2. Turn the engine switch on (IG).

  3. Turn the tester on.

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

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

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

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

  8. Drive the vehicle at approximately 60 km/h (38 mph) for 10 minutes or more [B].

    Tip:

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

    CAUTION:

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

  9. Enter the following menus: Powertrain / Engine and ECT / DTC [C].

  10. Read the pending DTCs.

    Tip:

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

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

  11. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

  12. Input the DTC: P0420 or P0430.

  13. Check the DTC judgment result.

    Tester 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

    N/A

    • Unable to perform DTC judgment

    • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit
    Tip:

    • 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 shows INCOMPLETE or N/A, perform steps [D] through [E].

  14. Drive the vehicle at a speed between 75 and 100 km/h (47 and 63 mph) for 10 minutes or more [D].

    Tip:

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

    CAUTION:

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

  15. Check the DTC judgment result again [E].

CONDITIONING FOR SENSOR TESTING

Tip:

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 to activate the sensors sufficiently to obtain appropriate inspection results.

A280873E01

  • (a) Connect the intelligent tester to the DLC3.

  • (b) Start the engine and warm it up with all the accessories switched off until the engine coolant temperature stabilizes.

  • (c) Run the engine at an engine speed of between 2500 rpm and 3000 rpm for at least 3 minutes.

  • (d) While running the engine at 3000 rpm for 2 seconds, and then 2000 rpm for 2 seconds, check the waveforms of the air fuel ratio and heated oxygen sensors using the intelligent tester.

Tip:

  • If the voltage output of either the air fuel ratio or heated oxygen sensor does not fluctuate, or there is a noise in the waveform of either sensor, 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, perform the Control the Injection Volume for A/F Sensor Active Test using the intelligent tester.

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

Table 1. Result of real-vehicle check

Engine Speed

3000 rpm (without load)

2000 rpm (during fuel-cut)

2000 rpm (revving up the engine)

AFS Voltage B1S1

3.263 to 3.302 V

4.996 V

3.195 V

O2S B1S2

0.820 to 0.835 V

0.015 V

0.820 V
A121610E52

CAUTION / NOTICE / HINT

Tip:

  • 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. 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.

PROCEDURE

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

    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester on.

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

    5. Read DTCs.

      Powertrain > Engine and ECT > Trouble Codes

      Result

      Result

      Proceed to

      P0420 or P0430 is output

      A

      P0420 or P0430 and other DTCs are output

      B
      Tip:

      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. Start the engine.

    3. Turn the tester on.

    4. Warm up the engine and run the engine at an engine speed of 2500 rpm for approximately 90 seconds.

    5. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the Injection Volume for A/F Sensor.

      Powertrain > Engine and ECT > Active Test

      Tester Display

      Control the Injection Volume for A/F Sensor

    6. Perform the Control the Injection Volume operation with the engine idling.

    7. 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.

      Tip:

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

      +12.5%

      Rich

      Below 3.1 V

      AFS Voltage B1S1 or AFS Voltage B2S1

      (Air fuel ratio)

      -12.5%

      Lean

      Higher than 3.4 V

      O2S B1S2 or O2S B2S2

      (Heated oxygen)

      +12.5%

      Rich

      Higher than 0.55 V

      O2S B1S2 or O2S B2S2

      (Heated oxygen)

      -12.5%

      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

      Suspected Trouble Area

      Proceed to

      Lean/Rich

      Lean/Rich

      Normal

      • Three-way catalytic converter

      • Gas leaks from exhaust system

      • EGR valve assembly

      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 leaks from exhaust system

      C

      Lean/Rich

      Rich

      Heated oxygen sensor malfunction

      • Heated oxygen sensor

      • Gas leaks from exhaust system

      Lean

      Lean

      Actual air fuel ratio lean

      • Extremely rich or lean actual air fuel ratio

      • Gas leaks from exhaust system

      • EGR valve assembly

      D

      Rich

      Rich

      Actual air fuel ratio lean

      • Extremely rich or lean actual air fuel ratio

      • Gas leaks from exhaust system

      • EGR valve assembly

      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 alternate correctly.

    8. 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 LEAKClick here

    D

    CHECK FOR EXHAUST GAS LEAKClick 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.

      Result

      Result

      OK

      NG
    NG

    REPAIR OR REPLACE EXHAUST GAS LEAK POINT

    OK

  4. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (CONTROL THE EGR STEP POSITION)

    1. Connect the intelligent tester to the DLC3.

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

      Tip:

      • When performing the Active Test, make sure the shift lever is in P or N.

      • The A/C switch and all accessory switches should be off.

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position.

      Powertrain > Engine and ECT > Active Test

      Tester Display

      Control the EGR Step Position

    5. Confirm that Throttle Idle Position is ON and check the engine idling condition and the value of MAP in the Data List while performing the Active Test.

      Tip:

      • Do not leave the EGR valve open for 10 seconds or more during the Active Test.

      • Be sure to return the EGR valve to step 0 when the Active Test is completed.

      OK

      MAP and idling condition change in response to EGR step position as follows.

      Standard

      -

      EGR Step Position (Active Test)

      Step 0

      Step 0 to 30

      Idling condition

      Steady idling

      Idling changes from steady to rough idling or engine stalls

      MAP

      (Data List)

      20 to 40 kPa (150 to 300 mmHg)

      MAP value is at least 10 kPa (75 mmHg) higher than when EGR valve is fully closed

      Result

      Result

      OK

      NG
    OK

    CHECK DTC OUTPUT (DTC P0420 AND/OR P0430)Click here

    NG

  5. INSPECT EGR VALVE ASSEMBLY

    1. Remove the EGR valve assembly.

      Click here

    2. Check if the EGR valve is stuck open.

      OK

      EGR valve is tightly closed.

      Result

      Result

      OK

      NG
    NG

    REPLACE EGR VALVE ASSEMBLY

    Click here

    OK

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

    1. According to the DTCs output above (Check for Any Other DTCs Output), proceed to the next step referring to the table below.

      Powertrain > Engine and ECT > Trouble Codes

      Result

      Result

      Proceed to

      P0420 is output

      A

      P0430 is output

      B

      P0420 and P0430 are output

      A and B
    A

    REPLACE EXHAUST MANIFOLD ASSEMBLY LH AND FRONT NO. 2 EXHAUST PIPE ASSEMBLY (TWC: FRONT CATALYST AND REAR CATALYST)

    Click here

    B

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

    Click here

  7. CHECK FOR EXHAUST GAS LEAK

    1. Inspect for exhaust gas leaks from the exhaust manifold assembly and exhaust pipes.

      OK

      No gas leaks.

      Result

      Result

      OK

      NG
    OK

    REPLACE HEATED OXYGEN SENSOR

    Click here

    NG

    REPAIR OR REPLACE EXHAUST GAS LEAK POINT

  8. CHECK FOR EXHAUST GAS LEAK

    1. Inspect for exhaust gas leaks from the exhaust manifold assembly and exhaust pipes.

      OK

      No gas leaks.

      Result

      Result

      OK

      NG
    NG

    REPAIR OR REPLACE EXHAUST GAS LEAK POINT

    OK

  9. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (CONTROL THE EGR STEP POSITION)

    1. Connect the intelligent tester to the DLC3.

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

      Tip:

      • When performing the Active Test, make sure the shift lever is in P or N.

      • The A/C switch and all accessory switches should be off.

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position.

      Powertrain > Engine and ECT > Active Test

      Tester Display

      Control the EGR Step Position

    5. Confirm that Throttle Idle Position is ON and check the engine idling condition and the value of MAP in the Data List while performing the Active Test.

      Tip:

      • Do not leave the EGR valve open for 10 seconds or more during the Active Test.

      • Be sure to return the EGR valve to step 0 when the Active Test is completed.

      OK

      MAP and idling condition change in response to EGR step position as follows.

      Standard

      -

      EGR Step Position (Active Test)

      Step 0

      Step 0 to 30

      Idling condition

      Steady idling

      Idling changes from steady to rough idling or engine stalls

      MAP

      (Data List)

      20 to 40 kPa (150 to 300 mmHg)

      MAP value is at least 10 kPa (75 mmHg) higher than when EGR valve is fully closed

      Result

      Result

      OK

      NG
    OK

    CHECK CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO

    NG

  10. INSPECT EGR VALVE ASSEMBLY

    1. Remove the EGR valve assembly.

      Click here

    2. Check if the EGR valve is stuck open.

      OK

      EGR valve is tightly closed.

      Result

      Result

      OK

      NG
    OK

    CHECK CAUSE OF EXTREMELY RICH OR LEAN ACTUAL AIR FUEL RATIO

    NG

    REPLACE EGR VALVE ASSEMBLY

    Click here