ECD SYSTEM, Diagnostic DTC:P0400

DTC Code DTC Name
P0400 Exhaust Gas Recirculation Flow

DESCRIPTION

The EGR system recirculates exhaust gases, and is controlled to the proper volume to be suitable for 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)

  • Difference between target and actual position of EGR valve is 10% or more for 10 seconds or more

    (1 trip detection logic)

  • Difference between target and actual position of EGR valve is 25% or more for 3 seconds or more

    (1 trip detection logic)

  • EGR valve stuck

  • EGR valve does not move smoothly

  • Open or short in VRV for EGR circuit

  • Open or short in EGR valve position sensor circuit

  • EGR valve position sensor

  • Vacuum pump

  • Vacuum hose connection loose

  • ECM

Tech Tips

DTC detection is not performed for 4 seconds after brake switch is turned ON or OFF.

MONITOR DESCRIPTION

When the target and actual positions of the EGR valve are different, the ECM interprets this as a malfunction of the EGR valve and illuminates the MIL.

A003GTAE01

WIRING DIAGRAM

A003GJCE02

INSPECTION PROCEDURE

Note

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

Tech Tips


  • 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 running or stopped, if the engine was warmed up or not, and other data from the time the malfunction occurred.

  • After warming up the engine, DTC P0400 is set 1 second or more after quickly accelerating the engine from idling.

PROCEDURE


  1. CHECK OTHER DTC OUTPUT


    1. Connect the GTS to the DLC3.

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

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

    4. Read DTCs.

      Result
      Tester Display Proceed to
      P0400 A
      P0400 and P0405 and/or P0406 B

      Tech Tips

      If any other codes besides DTC P0400 are output, perform troubleshooting for those DTCs first.


    B

    GO TO DTC CHART Click here

    A

  2. CHECK VACUUM PUMP ASSEMBLY


    1. Check the negative pressure of the vacuum pump Click here.

      Standard
      More than 86.7 kPa (650 mmHg, 26 in.Hg)

    NG

    REPLACE VACUUM PUMP ASSEMBLY

    OK

  3. CHECK VACUUM HOSES


    1. Check the vacuum hoses.

      OK
      The hoses are not damaged and securely connected.

    NG

    REPAIR OR REPLACE VACUUM HOSE

    OK

  4. CHECK TERMINAL VOLTAGE (VRV FOR EGR)


    1. A003CKUE18
      *a

      Front view of wire harness connector

      (to VRV for EGR)

      Disconnect the VRV for EGR connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      D55-1 - Body ground Ignition switch ON 11 to 14 V

    3. Reconnect the VRV for EGR connector.


    NG

    CHECK HARNESS AND CONNECTOR (VRV FOR EGR - NO. 1 INTEGRATION RELAY) Click here

    OK

  5. INSPECT ELECTRIC EGR CONTROL VALVE ASSEMBLY (VRV FOR EGR)


    1. Check the Electric EGR control valve assembly (VRV for EGR) Click here.


    NG

    REPLACE ELECTRIC EGR CONTROL VALVE ASSEMBLY (VRV FOR EGR) Click here

    OK

  6. CHECK HARNESS AND CONNECTOR (VRV FOR EGR - ECM)


    1. Disconnect the VRV for EGR connector.

    2. Disconnect the ECM connector.

    3. Measure the resistance of the wire harness side connectors.

      Standard Resistance
      Tester Connection Condition Specified Condition
      D55-2 - D105-83 (EGR) Always Below 1 Ω
      D55-2 or D105-83 (EGR) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

  7. INSPECT ELECTRIC EGR CONTROL VALVE ASSEMBLY (EGR VALVE ASSEMBLY)


    1. Check the EGR valve assembly Click here.

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

    NG

    REPLACE ELECTRIC EGR CONTROL VALVE ASSEMBLY (VRV FOR EGR) Click here

    OK

    REPLACE ECM Click here

  8. CHECK HARNESS AND CONNECTOR (VRV FOR EGR - NO. 1 INTEGRATION RELAY)


    1. Remove the No. 1 integration relay from the No. 1 engine room relay block and junction block assembly.

    2. Disconnect the integration relay connector.

    3. Disconnect the VRV for EGR connector.

    4. Measure the resistance of the wire harness side connectors.

      Standard Resistance
      Tester Connection Condition Specified Condition
      10B-4 - D55-1 Always Below 1 Ω
      10B-4 or D55-1 - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

    GO TO ECM POWER SOURCE CIRCUIT Click here