DTC P0400 2AD-FHV

DTC P0400 Exhaust Gas Recirculation Flow

 

Description

The EGR system recirculates exhaust gases, in order to suit every driving condition. The recirculated gas mingles with the intake air, therefore the EGR system can slow combustion speed and keep the combustion temperature down. This helps reduce NOx emissions.
In order to increase EGR circulation efficiency, the ECM adjusts the lift amount of the EGR valve and intake shutter valve angle (throttle valve).
Toyota fault code list DTC P0400

DTC No. DTC Detection Condition Trouble Area
P0400 Target and actual positions of the EGR valve is different
(1 trip detection logic)
  1. EGR valve stuck
  2. EGR valve does not move smoothly
  3. Open or short in EGR circuit
  4. Open or short in EGR valve position sensor circuit
  5. EGR valve position sensor
  6. ECM

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.


Monitor description DTC P0400

Wiring diagram


Wiring diagram DTC P0400

Inspection procedure

 

NOTICE:

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

HINT:

After warming up the engine, DTC P0400 can be set if 1 second or more passes after quickly accelerating the engine from idling.

1.CHECK OTHER DTC OUTPUT (IN ADDITION TO DTC P0400)
  1. Connect the intelligent tester to the DLC3.

  2. Turn the ignition switch on (IG) 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 P0405 and/or P0406 B

HINT:

If codes other than P0400 are output, perform troubleshooting for those DTCs first.

 

  B  
GO TO DTC CHART
 
A  
   
2.READ VALUE OF INTELLIGENT TESTER (EGR POSITION)
  1. Connect the intelligent tester to the DLC3.

  2. Turn the ignition switch on (IG) and turn the tester ON.

  3. Enter the following menus: Powertrain / Engine and ECT / Data List / EGR Position.

  4. Read the value.
     

     

    Result:
     
    Condition Result Proceed to
    After warming up the engine, quickly accelerate the engine from idle to 3,000 rpm by using the accelerator pedal Constant or changes slowly A
    Smooth changes from approximately 0% to approximately 50% B

    HINT:

    1. EGR valve closed: EGR Position is 0%
    2. EGR valve open: EGR Position is 65%

 

  B  
CHECK FOR INTERMITTENT PROBLEMS
 
A  
   
3.INSPECT EGR VALVE POSITION SENSOR (RESISTANCE)

Inspect egr valve position sensor (resistance)

  1. Disconnect the B54 EGR valve position sensor connector.

  2. Measure the resistance of the terminals of the EGR valve position sensor.

     

    Standard resistance:

    Tester Connection Condition Specified Condition
    B54-5 (EGRS) - B54-1 (+B) 20°C (68°F) Approximately 6.5 to 7.5 ?
  3. Reconnect the EGR valve position sensor connector.

 

  NG  
REPLACE EGR VALVE POSITION SENSOR
 
OK  
   
4.CHECK WIRE HARNESS (EGR VALVE POSITION SENSOR - ECM)

Check wire harness (egr valve position sensor - ecm)

  1. Disconnect the B54 EGR valve position sensor connector.

  2. Disconnect the B32 ECM connector.

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

     

    Standard resistance:

    Tester Connection Specified Condition
    B54-5 (EGRS) - B32-85 (EGRS) Below 1 ?
    B54-5 (EGRS) or B32-85 (EGRS) - Body ground 10 k? or higher
  4. Reconnect the EGR valve position sensor connector.

  5. Reconnect the ECM connector.

 

  NG  
REPAIR OR REPLACE HARNESS AND CONNECTOR
 
OK  
   
5.CHECK WIRE HARNESS (EGR VALVE POSITION SENSOR - INTEGRATION RELAY)

Check wire harness (egr valve position sensor - integration relay)

  1. Inspect the EFI NO. 1 fuse.

    1. Remove the EFI NO. 1 fuse from the engine room No. 1 relay block.

    2. Measure the resistance of the fuse.

       

      Standard resistance:

      Below 1 ?

    3. Reinstall the EFI NO. 1 fuse.

     

  2. Check the wire harness between the EGR valve position sensor and integration relay.

    1. Disconnect the B54 EGR valve position sensor connector.

    2. Remove the integration relay from the engine room No. 1 relay block.

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

       

      Standard resistance:

      Tester Connection Specified Condition
      B54-1 (+B) - 1A-4 Below 1 ?
      B54-1 (+B) or 1A-4 - Body ground 10 k? or higher
    4. Reconnect the EGR valve position sensor connector.

    5. Reinstall the integration relay.

 

  NG  
REPAIR OR REPLACE HARNESS AND CONNECTOR
 
OK  
   
6.REPLACE EGR VALVE POSITION SENSOR
  1. Replace the EGR valve position sensor .

 

NEXT  
   
7.CHECK WHETHER DTC OUTPUT RECURS
  1. Connect the intelligent tester to the DLC3.

  2. Turn the ignition switch on (IG) and turn the tester ON.

  3. Clear DTCs.

  4. Start the engine and drive the vehicle for approximately 15 minutes.

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

  6. Read the DTCs.

     

    Result:
    Display (DTC Output) Proceed to
    P0400 A
    No output B

 

  B  
SYSTEM IS OK
 
A  
   
REPLACE ECM