DTC P0401: Exhaust Gas Recirculation Flow Insufficient Detected [08/2014 - ]: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
5. Read the DTC.

   Result

   Result	Proceed to
   DTC P0401 is output	A
   DTC P0401 and other DTCs are output	B

   HINT: 

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

B → See step   12 

A: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Put the engine in inspection mode (maintenance mode). Refer to INSPECTION MODE PROCEDURE [08/2014 - ] .
5. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

   HINT: 

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

6. Enter the following menus: Powertrain / Engine and ECT / Active Test / Control the EGR Step Position / Throttle Idle Position and MAP.
7. Check that the Throttle Idle Position in ON and check the MAP values in the Data List while performing the Active Test.

   HINT: 

   • 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.

   OK

   MAP change in response to EGR step position when Throttle Idle Position is ON in Data List.

   Standard

   -	EGR Step Position (Active Test)
   	0 Steps	0 to 30 Steps
   MAP (Data List)	(EGR valve is fully closed)	MAP value is at least +10 kPa (75 mmHg) higher than when EGR valve is fully closed

   HINT: 

   • While performing the Active Test, if the increase in the value of MAP is small, the EGR valve assembly may be a malfunctioning.
   • Even if the EGR valve assembly is malfunctioning, rough idling or an increase in the value of MAP may occur while performing the Active Test. However, the amount that the value of MAP increases will be smaller than normal.

NG → See step   4 

OK: Go to next step 

1. Check if the EGR valve are clogged with deposits.
2. Check if the EGR valve is closed.

   OK

   EGR valve is closed and no deposits.

   Result

   Result	Proceed to
   NG	A
   OK	B

B → See step   5 

A: Go to next step 

1. Replace the EGR valve assembly. Refer to REMOVAL [08/2014 - ] .

   HINT: 

   Perform "Inspection After Repair" after replacing the EGR valve assembly. Refer to INITIALIZATION [08/2014 - ] .

NEXT: Go to next step 

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Check for exhaust 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.

   HINT: 

   Perform "Inspection After Repair" after repairing or replacing the exhaust system. Refer to INITIALIZATION [08/2014 - ] .

NG → REPAIR OR REPLACE MALFUNCTIONING PARTS, COMPONENT AND AREA 

OK: Go to next step 

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

1. Check for exhaust leaks at each connection point.
2. Check for cracks, damage, and clogs in the pipes between the exhaust manifold 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.

   HINT: 

   Perform "Inspection After Repair" after repairing or replacing the exhaust system. Refer to INITIALIZATION [08/2014 - ] .

NG → REPAIR OR REPLACE MALFUNCTIONING PARTS, COMPONENT AND AREA 

OK: Go to next step 

1. Check for blockage of the EGR pipe with cooler sub-assembly.

NG → REPAIR OR REPLACE EGR PIPE WITH COOLER SUB-ASSEMBLY 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / MAP.
5. Read the MAP value.

   Standard

   Switch Condition	Techstream Display
   Power switch on (IG)	80 to 110 kPa(abs) [600 to 825 mmHg(abs)]

6. Put the engine in inspection mode (maintenance mode). Refer to INSPECTION MODE PROCEDURE [08/2014 - ] .
7. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.
8. Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / MAP.
9. Read the MAP value when idling the engine with the A/C switch and all accessory switches should be off and shift position in P or N.

   Standard

   Engine Condition	Techstream Display
   Idling	Less than 80 kPa(abs) [800 mmHg(abs)]

   Result

   Result	Proceed to
   NG	A
   OK	B

B → See step   11 

A: Go to next step 

1. Check the intake system for vacuum leaks. Refer to ON-VEHICLE INSPECTION [08/2014 - ] .

   OK

   No leaks in intake system.

   HINT: 

   Perform "Inspection After Repair" after repairing or replacing the intake system. Refer to INITIALIZATION [08/2014 - ] .

NG → REPAIR OR REPLACE INTAKE SYSTEM 

OK: Go to next step 

1. Replace the manifold absolute pressure sensor. Refer to REMOVAL [08/2014 - ] .

NEXT: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the power switch on (IG).
3. Turn the Techstream on.
4. Clear the DTCs. Refer to DTC CHECK / CLEAR [08/2014 - ] .
5. Turn the power switch off and wait for at least 30 seconds.
6. Turn the power switch on (IG).
7. Turn the Techstream on.
8. Drive the vehicle in accordance with the driving pattern described in the Confirmation Driving Pattern.
9. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes / Pending.
10. Read the pending DTCs.

    HINT: 

    • If the pending DTC is output, the system is malfunctioning.
    • If a pending DTC is not output, perform the following procedure.
11. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
12. Input the DTC: P0401.
13. Check the DTC judgment result.

    Techstream 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

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