ECD SYSTEM, Diagnostic DTC:P0400

DTC Code DTC Name
P0400 Exhaust Gas Recirculation Flow

DESCRIPTION

The EGR system recirculates exhaust gases, in order to suit every driving condition. The recirculated gas mingles with intake air, therefore the EGR system can slow combustion speed and keep the combustion temperature down. This helps reduce NOx emission.

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

P0400
DTC Detection Drive Pattern DTC Detection Condition Trouble Area

Drive the vehicle at an engine speed of 1700 to 1800 rpm and fuel quantity of 68 to 80 mm3/st.

EGR air flow rate less than the specified value when following conditions (a), (b), (c), (d), (e) and (f) are met (2 trip detection logic):

(a) Engine speed is stable

(b) Fuel quantity is stable

(c) Intake air amount is stable

(d) EGR valve assembly opening angle is 5% or more

(e) Exhaust brake system does not operate

(f) Mass air flow meter sub-assembly circuit malfunction, EGR valve assembly circuit malfunction, manifold absolute pressure sensor circuit malfunction and intake air temperature sensor (after turbocharged) circuit malfunction are not detected

  • EGR valve assembly stuck

  • Open or short in EGR valve assembly circuit

  • EGR valve assembly does not move smoothly

  • EGR valve assembly deposit

  • EGR valve assembly passage deposit

  • EGR cooler sub-assembly

  • Air intake system (leaks or blockages)

  • Exhaust gas leaks

  • ECM

MONITOR DESCRIPTION

If the EGR valve assembly is forcibly operated but the intake air amount does not vary, the ECM determines that the EGR valve assembly is malfunctioning. The ECM then illuminates the MIL.

WIRING DIAGRAM

A01CHVSE02

INSPECTION PROCEDURE

Note


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

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

Tech Tips


  • When this DTC is stored the vehicle enters fail-safe mode, in which the MIL blinks and the ECM measures elapsed time until an idle signal has been input or engine speed is below 200 rpm after 36 hours, after which engine output is limited to 75%.

  • 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 be helpful in determining whether the vehicle was moving or stationary, whether the engine was warmed up or not, as well as other data recorded at the time of a malfunction.

PROCEDURE


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


    1. Replace the normal DLC3 cable (12 V specification) for the intelligent tester with the 24 V DLC3 cable.

      Note

      Be sure to use the 24 V DLC3 cable when connecting the intelligent tester to the DLC3. Using the normal DLC3 cable (12 V specification) will cause damage to the tester.

    2. Connect the intelligent tester to the DLC3.

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

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

    5. Read the DTCs.

      Result
      Result Proceed To
      DTC P0400 is output A
      DTC P0400 and other DTCs are output B

      Tech Tips

      If any DTCs other than P0400 are output, troubleshoot those DTCs first.


    B

    GO TO DTC CHART Click here

    A

  2. CHECK FOR EXHAUST GAS LEAKS


    1. Check for exhaust gas leaks.

      Result
      Result Proceed To
      Exhaust gas leaks out from exhaust system A
      No leaks B

    B

    CHECK AIR INTAKE SYSTEM (AIR LEAKS AND BLOCKAGES) Click here

    A

  3. REPAIR EXHAUST GAS LEAK POINT


    1. Repair or replace the malfunctioning part in the exhaust system.


    NEXT

  4. CHECK AIR INTAKE SYSTEM (AIR LEAKS AND BLOCKAGES)


    1. Check for air leaks and blockages in the air intake system.

      Result
      Result Proceed To
      Leaks or blockages exist in the air intake system A
      No leaks or blockages in the air intake system B

      Tech Tips


      • Check for abnormal disconnection, pipe and hose squashing, and any damages in the air intake system.

      • Using your hand, check whether the pipes and hoses in the air intake system are securely connected.

      • Applying soapy water and revving the engine, air leaks from the air intake system can be checked.

      • Check for any modifications in the air intake system made by the user.


    B

    PERFORM ACTIVE TEST USING INTELLIGENT TESTER (CONTROL THE EGR SYSTEM) Click here

    A

  5. REPAIR OR REPLACE AIR INTAKE SYSTEM


    1. Repair or replace the malfunctioning part in the air intake system.


    NEXT

  6. PERFORM ACTIVE TEST USING INTELLIGENT TESTER (CONTROL THE EGR SYSTEM)


    1. Turn the ignition switch off and wait for 60 seconds.

    2. Replace the normal DLC3 cable (12 V specification) for the intelligent tester with the 24 V DLC3 cable.

      Note

      Be sure to use the 24 V DLC3 cable when connecting the intelligent tester to the DLC3. Using the normal DLC3 cable (12 V specification) will cause damage to the tester.

    3. Connect the intelligent tester to the DLC3.

    4. Start the engine and turn the tester on.

    5. Warm up the engine until the engine coolant temperature reaches 80°C (176°F).

    6. Enter the following menus: Powertrain / Engine and ECT / Active Test / Activate the EGR Valve Close / Data List / MAF.

    7. Read the value.

      Result
      Active Test Result Proceed to
      Activate the EGR Valve Close: Off (Open) to Close (Closed) MAF value is not changed A
      MAF value is changed B

      Note

      In the table below, the values listed under "MAF Value" are reference values. Do not depend solely on these reference values when deciding whether a part is faulty or not.

      Reference
      EGR Valve Status Condition MAF Value
      Open (21%)

      Atmospheric pressure: 101 kPa

      Intake air temperature: 25°C (77°F)

      Engine coolant temperature: 76°C (169°F)

      		 10 to 12 gm/sec
      Close (0%) 15 to 17 gm/sec

    B

    INSPECT EGR VALVE ASSEMBLY (EGR VALVE OPERATION) Click here

    A

  7. CHECK HARNESS AND CONNECTOR (EGR VALVE ASSEMBLY - BODY GROUND)


    1. Disconnect the EGR valve assembly connector.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      E31-1 (E) - Body ground Always Below 1 Ω

    3. Reconnect the EGR valve assembly connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (EGR VALVE ASSEMBLY - BODY GROUND)

    OK

  8. CHECK EGR VALVE ASSEMBLY (POWER SOURCE)


    1. A01CILYE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to EGR Valve Assembly)

      Disconnect the EGR valve assembly connector.

    2. Turn the ignition switch to ON.

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      E31-4 (+B) - Body ground Ignition switch ON 18 to 27 V

    4. Reconnect the EGR valve assembly connector.


    NG

    CHECK HARNESS AND CONNECTOR (EGR VALVE ASSEMBLY - ENG ACT RELAY) Click here

    OK

  9. INSPECT EGR VALVE ASSEMBLY (EGR VALVE OPERATION)


    1. Remove the EGR valve assembly.

    2. Inspect the EGR valve assembly.


      1. Visually check the EGR valve assembly for deposits.

        OK
        No deposits around the EGR valve.

      2. Visually check that there is no gap between the valve and body.

        OK
        No gap between the valve and body.
        Result
        Result Proceed To
        NG A
        OK B

    3. Reinstall the EGR valve assembly.


    B

    CHECK FOR BLOCKAGE IN EGR GAS PASSAGE (EXHAUST MANIFOLD - EGR COOLER - EGR VALVE ASSEMBLY) Click here

    A

  10. REPLACE EGR VALVE ASSEMBLY


    1. Replace the EGR valve assembly Click here.


    NEXT

  11. CHECK FOR BLOCKAGE IN EGR GAS PASSAGE (EXHAUST MANIFOLD - EGR COOLER - EGR VALVE ASSEMBLY)


    1. Check for blockage in the EGR gas passage from the exhaust manifold, through the EGR cooler sub-assembly to the EGR valve assembly.

      OK
      No blockage in the EGR gas passage.
      Result
      Result Proceed To
      NG A
      OK B

    B

    CHECK WHETHER DTC OUTPUT RECURS Click here

    A

  12. REPAIR OR REPLACE MALFUNCTIONING PARTS, COMPONENT AND AREA


    1. Repair or replace the malfunctioning parts, component and area.


    NEXT

  13. CHECK WHETHER DTC OUTPUT RECURS


    1. Replace the normal DLC3 cable (12 V specification) for the intelligent tester with the 24 V DLC3 cable.

      Note

      Be sure to use the 24 V DLC3 cable when connecting the intelligent tester to the DLC3. Using the normal DLC3 cable (12 V specification) will cause damage to the tester.

    2. Connect the intelligent tester to the DLC3.

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

    4. Start the engine and warm it up until the engine coolant temperature reaches 80°C (176°F).

    5. Drive the vehicle at 50 km/h (31 mph) or more and then fully release the accelerator pedal for 5 seconds or more (Procedure "A").

    6. Repeat procedure "A" several times.

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

    8. Read the DTC.

      Result
      Result Proceed To
      DTC P0400 is output A
      DTC is not output B

    B

    END

    A

  14. REPLACE EGR COOLER SUB-ASSEMBLY


    1. Replace the EGR cooler sub-assembly Click here.


    NEXT

  15. CHECK WHETHER DTC OUTPUT RECURS


    1. Replace the normal DLC3 cable (12 V specification) for the intelligent tester with the 24 V DLC3 cable.

      Note

      Be sure to use the 24 V DLC3 cable when connecting the intelligent tester to the DLC3. Using the normal DLC3 cable (12 V specification) will cause damage to the tester.

    2. Connect the intelligent tester to the DLC3.

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

    4. Start the engine and warm it up until the engine coolant temperature reaches 80°C (176°F).

    5. Drive the vehicle at 50 km/h (31 mph) or more and then fully release the accelerator pedal for 5 seconds or more (Procedure "A").

    6. Repeat procedure "A" several times.

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

    8. Read the DTC.

      Result
      Result Proceed To
      DTC P0400 is output A
      DTC is not output B

    B

    END

    A

    REPLACE ECM Click here

  16. CHECK HARNESS AND CONNECTOR (EGR VALVE ASSEMBLY - ENG ACT RELAY)


    1. Disconnect the EGR valve assembly connector.

    2. Remove the ENG ACT relay from the engine room relay block and junction block.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for Open)
      Tester Connection Condition Specified Condition
      E31-4 (+B) - ENG ACT relay terminal 5 Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      E31-4 (+B) or ENG ACT relay terminal 5 - Body ground Always 10 kΩ or higher

    4. Reconnect the EGR valve assembly connector.

    5. Reinstall the ENG ACT relay.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (EGR VALVE ASSEMBLY - ENG ACT RELAY)

    OK

    CHECK POWER SOURCE CIRCUIT Click here