ECD SYSTEM (w/o DPF), Diagnostic DTC:P0400

DTC Code DTC Name
P0400 Exhaust Gas Recirculation Flow

DESCRIPTION

The EGR system recirculates exhaust gases, and performs control so that the proper volume of exhaust gas is recirculated to suit all driving conditions. The recirculated gas mixes with the intake air, allowing the EGR system to slow down engine combustion and lower the combustion temperature. This helps reduce NOx emissions.

In order to increase circulation efficiency, the ECM adjusts the lift amount of the EGR valve and throttle valve.

P0400
DTC Detection Drive Pattern DTC Detection Condition Trouble Area
Decelerate from a speed of 50 km/h (80 mph) or more (release accelerator pedal for approximately 5 seconds) Mass air flow rate is not changed when the EGR valve is turned on (2 trip detection logic).

  • EGR valve stuck

  • EGR valve does not move smoothly

  • Electric vacuum regulating valve assembly

  • Vacuum switching valve (for EGR Cut)

  • Electric vacuum regulating valve assembly circuit

  • Vacuum switching valve (for EGR Cut) circuit

  • EGR blockage in line between exhaust manifold and intake manifold

  • Mass air flow meter

  • Intake system (leaks or blockages)

  • EGR cooler

  • Exhaust system (exhaust gas leaks)

  • ECM
Related Data List
DTC No. Data List
P0400

  • MAF

  • MAP

  • Actual EGR Valve Pos.

  • Target EGR Position

  • EGR Close Lrn. Val.

  • EGR Close Learn Val.

  • EGR Close Lrn. Status

  • EGR Lift Sensor Output

MONITOR DESCRIPTION



A00O4POE03

WIRING DIAGRAM

A00O55XE01

INSPECTION PROCEDURE

Note


  • Inspect the fuses for circuits related to this system before performing the following inspection procedures.

  • After replacing the ECM, the new ECM needs registration Click here and initialization Click here.

Tech Tips

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, and other data from the time the malfunction occurred.

PROCEDURE


  1. CHECK FOR ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0400)


    1. Connect the intelligent tester to the DLC3.

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

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

    4. Read DTCs.

      Result
      Display (DTC Output) Proceed to
      P0400 A
      P0400 and other DTCs B

    B

    GO TO DTC CHART Click here

    A

  2. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (ACTIVATE THE VSV FOR EGR CUT)


    1. Connect the intelligent tester to the DLC3.

    2. Start the engine and warm it up, and make sure the A/C switch and all accessory switches are off.

    3. Turn the ignition switch off. Wait for 30 seconds, and then restart the engine.

    4. Turn the tester on.

    5. Enter the following menus: Powertrain / Engine and ECT / Data List / MAF.

    6. Read the MAF value displayed on the tester while the engine is idling.

    7. Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the VSV for EGR Cut or Activate the EGR valve Close.

    8. Read the mass air flow meter value when the VSV for EGR Cut or electric vacuum regulating valve assembly is turned from off to on using the Active Test function.

      Tech Tips


      • If idling continues for 15 minutes or more, the EGR valve target opening angle becomes 0% (EGR valve fully closed). As this makes diagnosis impossible, it becomes necessary to drive the vehicle or to restart the engine.

      • Before performing the diagnosis, confirm that the EGR valve target opening angle is not 0%.

      • When "Coolant Temp" is 75°C (167°F) or higher during idling, the exhaust gas flows through the EGR cooler. If MAF does not change when the EGR is cut even though the EGR valve is operating normally, the EGR cooler may be clogged.

      • When idling while warming up the engine, the actuator operates and the EGR cooler is bypassed. However, if the connector of the VSV for the EGR cooler is disconnected, the EGR cooler is not bypassed and it is possible to check how clogged the EGR cooler is.

      Result
      Active Test Result Proceed to

      Activate the VSV for EGR Cut:

      Off (Open) to on (Close)

      		 MAF value does not change A
      MAF value changes B

      Note

      As the values shown below may differ due to factors such as differences in measuring environments and changes in vehicle condition due to aging, do not use these values to determine whether the vehicle is malfunctioning or not.

      Tech Tips

      The problem may be a temporary one, due to the entry of deposits or foreign matter. Check that there are no deposits or foreign matter in the electric vacuum regulating valve assembly or mass air flow meter.

      Reference
      EGR Valve Condition (Opening) Measuring Condition MAF (Reference)
      Open (55%)

      • Atmosphere pressure: 101 kPa

      • Intake air temperature: 30°C (86°F)

      • Engine coolant temperature: 88°C (190°F)

      		 4.5 to 10.5 g/sec
      Close (0%) 13 to 20 g/sec

    B

    INSPECT ELECTRIC EGR CONTROL VALVE ASSEMBLY (EGR VALVE OPERATION) Click here

    A

  3. CHECK VACUUM HOSES


    1. Check the vacuum hoses.

      OK
      The hoses are not damaged and are securely connected

    NG

    REPAIR OR REPLACE VACUUM HOSE Click here

    OK

  4. INSPECT ELECTRIC VACUUM REGULATING VALVE ASSEMBLY


    1. Inspect the electric vacuum regulating valve assembly Click here.

      Tech Tips

      Before replacing the electric vacuum regulating valve assembly, perform a wire harness inspection and if there are any problems with the wire harness, repair or replace it.


    NG

    REPLACE ELECTRIC EGR CONTROL VALVE ASSEMBLY Click here

    OK

  5. INSPECT VACUUM SWITCHING VALVE (FOR EGR CUT)


    1. Inspect the vacuum switching valve (for EGR cut) Click here.

      Tech Tips

      Before replacing the vacuum switching valve (for EGR cut), perform a wire harness inspection and if there are any problems with the wire harness, repair or replace it.


    NG

    REPLACE VACUUM SWITCHING VALVE ASSEMBLY (FOR EGR CUT) Click here

    OK

  6. INSPECT ELECTRIC EGR CONTROL VALVE ASSEMBLY (EGR VALVE OPERATION)


    1. Inspect the electric EGR control valve assembly Click here.

      OK
      The valve is not stuck and does not have heavy carbon deposits

    NG

    REPLACE ELECTRIC EGR CONTROL VALVE ASSEMBLY Click here

    OK

  7. CHECK FOR DEPOSIT (EGR PASSAGE)


    1. Check the deposit conditions in the EGR cooler and the EGR passage.

      OK
      The EGR passage is not clogged and does not have heavy carbon deposits

      Tech Tips

      When performing the check for deposits, check the interior of the EGR valve, EGR pipe, EGR cooler, EGR cooler bypass valve and the entire EGR passage.


    OK

    CHECK WHETHER DTC OUTPUT RECURS (DTC P0400) Click here

    NG

    REPAIR OR REPLACE MALFUNCTIONING PARTS Click here

  8. REPAIR OR REPLACE VACUUM HOSE


    1. Repair or replace the vacuum hose.


    NEXT

    CHECK WHETHER DTC OUTPUT RECURS (DTC P0400) Click here

  9. REPLACE ELECTRIC EGR CONTROL VALVE ASSEMBLY


    1. Replace the electric EGR control valve assembly Click here.


    NEXT

    CHECK WHETHER DTC OUTPUT RECURS (DTC P0400) Click here

  10. REPLACE VACUUM SWITCHING VALVE ASSEMBLY (FOR EGR CUT)


    1. Replace the vacuum switching valve (for EGR cut).


    NEXT

    CHECK WHETHER DTC OUTPUT RECURS (DTC P0400) Click here

  11. REPAIR OR REPLACE MALFUNCTIONING PARTS


    NEXT

  12. CHECK WHETHER DTC OUTPUT RECURS (DTC P0400)


    1. Connect the intelligent tester to the DLC3.

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

    3. Clear DTCs Click here.

    4. Turn the ignition switch off for 30 seconds or more.

    5. Start the engine and warm it up.

    6. Move the shift lever to 2nd gear and decelerate from a speed of 50 km/h (31 mph) or more (fully release the accelerator for approximately 5 seconds or more).

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

    8. Read DTCs.

      Tech Tips

      When a DTC is output, the mass air flow meter may be malfunctioning.


    NEXT

    END