SFI SYSTEM, Diagnostic DTC:P0401

DTC Code DTC Name
P0401 Exhaust Gas Recirculation Flow Insufficient Detected

DESCRIPTION

Based on the driving conditions, the ECM regulates the volume of exhaust gas that is recirculated to the engine's combustion chambers and thus lowers the combustion temperature to reduce NOx emissions. The ECM monitors signals such as engine speed, engine coolant temperature, electric load, and vehicle speed. When the EGR permission conditions are fulfilled, the ECM controls the opening of the EGR valve linearly through signals to the EGR step motor.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

P0401

Exhaust Gas Recirculation Flow Insufficient Detected

Change in intake manifold pressure is small when the EGR valve opened and closed during fuel cut operation

(2 trip detection logic).

  • EGR valve assembly

  • EGR passage

  • Manifold absolute pressure sensor

  • ECM

Comes on (Euro-OBD) / - (except Euro-OBD)

DTC stored (Euro-OBD) / - (except Euro-OBD)

MONITOR DESCRIPTION

The ECM monitors the pressure inside the intake manifold while opening and closing the EGR valve during fuel cut operation. If there is no change in the manifold absolute pressure sensor value, the ECM interprets this as a malfunction in the EGR valve assembly, illuminates the MIL and stores the DTC (2 trip detection logic).

MONITOR STRATEGY

Required Sensors/Components (Main)

EGR valve assembly

Manifold absolute pressure sensor

Required Sensors/Components (Related)

Engine coolant temperature sensor

Vehicle speed sensor

Frequency of Operation

Once per driving cycle

TYPICAL ENABLING CONDITIONS

Engine speed

1200 to 3500 rpm

Vehicle speed

45 km/h (28 mph) or more

Intake air temperature

-10°C (14°F) or higher

TYPICAL MALFUNCTION THRESHOLDS

Manifold pressure change

Less than 2.0 kPa(gauge) [15.0 mmHg(gauge)]

At engine speed

1200 rpm

CONFIRMATION DRIVING PATTERN

A219133E07

  1. Connect the GTS to the DLC3.

  2. Turn the ignition switch to ON and turn the GTS on.

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

  4. Turn the ignition switch off and wait for at least 30 seconds.

  5. Turn the ignition switch to ON and turn the GTS on [A].

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

  7. Drive the vehicle at 60 km/h (37 mph) or more for 5 minutes or more [C].

    CAUTION:

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

  8. Idle the engine for 30 seconds or more [D].

  9. Accelerate the vehicle to 60 km/h (37 mph) with the transaxle to 2nd gear [E].

    CAUTION:

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

  10. Perform the fuel cut operation for 5 seconds or more, with the accelerator pedal fully released [F].

  11. (a) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending [G].

  12. 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.

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

  14. Input the DTC P0401.

  15. 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

    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 DTC judgment result is INCOMPLETE or N/A and no pending DTC is output, accelerate the vehicle again at 60 km/h (37 mph) and transaxle the 2nd gear to perform fuel cut operation for 5 seconds or more with the accelerator pedal fully released, and check the DTC judgment result.

WIRING DIAGRAM

Refer to DTC P0403.

Click here

CAUTION / NOTICE / HINT

Tip:

  • By using the Control the EGR Step Position Active Test, the operation of the EGR valve can be checked.

  • If the EGR valve is normal, the engine condition is as follows:

    The engine idles steady while the EGR valve is fully closed. When the EGR valve is opened using the Active Test, the Data List values will change as shown in the table below.

    Data List

    Change in Data List when Number of Steps is Increased Using Control the EGR Step Position Active Test

    Engine Speed

    Idle becomes rough

    MAP

    Pressure rises

  • 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 P0401)

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

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

    5. Read the DTC.

      Powertrain > Engine and ECT > Trouble Codes

      Result

      Result

      Proceed to

      DTC P0401 is output

      A

      DTC P0401 and other DTCs are output

      B
      Tip:

      If any DTCs other than P0401 are output, troubleshoot those DTCs first.

    B

    GO TO DTC CHART

    Click here

    A

  2. PERFORM ACTIVE TEST USING GTS (CONTROL THE EGR STEP POSITION)

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

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

      Tip:

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

    5. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position / All Data / MAP and Throttle Idle Position.

      Powertrain > Engine and ECT > Active Test

      Active Test Display

      Control the EGR Step Position

      Data List Display

      MAP

      Throttle Idle Position

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

      OK

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

      -

      EGR Step Position (Active Test)

      0 Steps

      0 to 30 Steps

      Idling condition

      Steady idling

      Idling changes from steady to rough idling or engine stalls

      MAP

      (Data List)

      MAP value is 20 to 48 kPa(abs)

      [150 to 360 mmHg(abs)]

      (EGR valve is fully closed)

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

      • Do not open the EGR valve 30 steps or more during the Active Test.

      • During Active Test, if the idling condition does not change in response to EGR step position, then there is probably a malfunction in the EGR valve assembly.

    Result

    Proceed to

    OK

    NG
    NG

    REPLACE EGR VALVE ASSEMBLYClick here

    OK

  3. 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

    Proceed to

    OK

    NG
    OK

    CHECK FOR DEPOSIT (EXHAUST MANIFOLD CONVERTER SUB-ASSEMBLY TO EGR VALVE ASSEMBLY)Click here

    NG

  4. REPLACE EGR VALVE ASSEMBLY

    1. Replace the EGR valve assembly.

      Click here

      Tip:

      Perform "Inspection After Repair" after replacing the EGR valve assembly.

      Click here

    Result

    Proceed to

    NEXT
    NEXT

  5. CHECK FOR DEPOSIT (EXHAUST MANIFOLD CONVERTER SUB-ASSEMBLY TO EGR VALVE ASSEMBLY)

    A284090

    1. Check for exhaust gas leaks at each connection point.

    2. Check for cracks, damage, and clogs in the pipes between the exhaust manifold converter sub-assembly and the EGR valve assembly.

    3. This check may require the removal of components.

    4. Check if there is a built-up of deposits in the EGR valve of pipes.

      OK

      No deposits

      Tip:

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

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE MALFUNCTIONING PARTS, COMPONENTS AND AREAS

    OK

  6. CHECK FOR DEPOSIT (INTAKE PORT TO EGR VALVE ASSEMBLY)

    A284089

    1. Check for exhaust gas leaks at each connection point.

    2. Check for cracks, damage, and clogs in the pipes between the intake manifold and the EGR valve assembly.

    3. This check may require the removal of components.

    4. Check if there is a built-up of deposits in the EGR valve of pipes.

      OK

      No deposits

      Tip:

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

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE MALFUNCTIONING PARTS, COMPONENTS AND AREAS

    OK

  7. READ VALUE USING GTS (MAP)

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAP.

      Powertrain > Engine and ECT > Data List

      Tester Display

      MAP

    5. Read the MAP value.

      Standard

      Engine condition

      GTS Display

      Ignition switch ON

      80 to 110 kPa(abs) [600 to 825 mmHg(abs)]

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

    7. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAP and Throttle Idle Position.

      Powertrain > Engine and ECT > Data List

      Tester Display

      MAP

      Throttle Idle Position

    8. Confirm the Throttle Idle Position is ON and check the engine idling condition and MAP when idling the engine with the A/C switch and all accessory switches should be off and shift lever in neutral.

      Standard

      Engine condition

      GTS Display

      Idling

      20 to 48 kPa(abs) [150 to 360 mmHg(abs)]

    Result

    Proceed to

    OK

    NG
    OK

    CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIREDClick here

    NG

  8. CHECK INTAKE SYSTEM

    1. Check the intake system for vacuum leaks.

      Click here

      OK

      No leaks in intake system.

      Tip:

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

      Click here

    Result

    Proceed to

    OK

    NG
    NG

    REPAIR OR REPLACE INTAKE SYSTEM

    OK

  9. REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR

    1. Replace the manifold absolute pressure sensor.

      Click here

    Result

    Proceed to

    NEXT
    NEXT

  10. CONFIRM WHETHER MALFUNCTION HAS BEEN SUCCESSFULLY REPAIRED

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Clear the DTCs.

      Powertrain > Engine and ECT > Clear DTCs

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

    6. Turn the ignition switch to ON.

    7. Turn the GTS on.

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

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

      Powertrain > Engine and ECT > Utility

      Tester Display

      All Readiness

    10. Input the DTC: P0401.

    11. Check the DTC judgment result.

      Table 1. 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

      N/A

      • Unable to perform DTC judgment

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

    Result

    Proceed to

    NEXT
    NEXT

    END