DTC P0401 Exhaust Gas Recirculation (EGR) Flow Insufficient Detected (4JJ3 with DPD)

1. Engine control system check

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 with DPD) Diagnostic system check-engine controls".

2. Current DTC check

1) Connect the scan tool.

2) Turn OFF the ignition switch for 1 minute or more.

3) Start the engine.

4) Operate the vehicle under the conditions for running the DTC.

5) Observe the DTC information with a scan tool. Is a DTC set?

Yes

=>Go to Prioritized DTC check.

No

Go to Intermittent conditions of engine.

Refer to "202.Engine 15D.Symptom(4JJ3 with DPD) intermittent conditions of engine".

3. Prioritized DTC check

1) Observe the DTC information with a scan tool. Is DTC P007C, P007D, P0101, P0234, P0299, P041C, P041D, or P2457 set at the same time?

Yes

Go to the applicable DTC diagnosis.

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 with DPD) DTC P007C CAC Outlet Temperature Sensor Circuit Low".

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 with DPD) DTC P007D CAC Outlet Temperature Sensor Circuit High".

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 with DPD) DTC P0101 Mass Air Flow Circuit Range/Performance".

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 with DPD) DTC P0234 Turbocharger Overboost Condition".

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 with DPD) DTC P0299 Turbocharger Underboost".

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 with DPD) DTC P041C Exhaust Gas Recirculation (EGR) Temperature Sensor Circuit Low".

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 with DPD) DTC P041D Exhaust Gas Recirculation (EGR) Temperature Sensor Circuit High".

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 with DPD) DTC P2457 Exhaust Gas Recirculation (EGR) Cooling System Performance".

No

=>Go to Turbocharger operation check.

4. Turbocharger operation check

1) Perform the Turbocharger with a scan tool.

2) Check visually the operation of the control rod while commanding the Desired Turbocharger Position parameter OPEN/CLOSE in steps. Does the control rod operate smoothly?

Yes

=>Go to EGR components inspection.

No

=>Go to Turbocharger inspection.

5. Turbocharger inspection

1) Inspect the turbocharger for the following. Is the result normal?

  • Abnormal conditions such as damage or breakage of the turbocharger
  • Abnormal conditions such as damage, breakage, or improper installation of the VGS actuator
  • Abnormal conditions such as damage, breakage, or looseness of the control rod section

Refer to "1.Engine 1F.Induction(4JJ3 with DPD) Turbocharger inspection".

Yes

Replace the turbocharger.

Refer to "1.Engine 1F.Induction(4JJ3 with DPD) Turbocharger removal".

Refer to "1.Engine 1F.Induction(4JJ3 with DPD) Turbocharger installation".

=>Go to Repair verification.

No

Repair as necessary.

=>Go to Repair verification.

6. EGR components inspection

1) Inspect the air intake/exhaust system for the following. Is the result normal?

  • Missing or damaged EGR valve gasket
  • Stuck EGR valve
  • EGR gas leakage from the EGR passage between the exhaust manifold and the inlet manifold
  • Collapsed or restricted flow in the EGR passage between the exhaust manifold and the EGR valve
  • Conditions that restrict exhaust system flow
  • Clogged air cleaner element, collapsing of the air intake piping between the air cleaner and inlet manifold, or a state where flow is restricted or breakage is present
  • Leakage in the air intake system
  • Water in the air intake system
  • Dirt or foreign material blocking the inlet of the MAF sensor
  • Misdetection or delayed response of the MAF sensor
  • Stuck intake throttle valve
  • Ventilation duct connected to the exhaust tail pipe Remove and inspect again if it is connected.

Yes

=>Go to EGR valve operation check using scan tool.

No

Repair or replace as necessary.

=>Go to Repair verification.

7. EGR valve operation check using scan tool

1) Perform the EGR Solenoid with a scan tool.

2) While observing the Desired Exhaust Gas Recirculation (EGR) Valve Position parameter and Exhaust Gas Recirculation (EGR) Valve Position parameter on the scan tool, command the EGR valve OPEN/CLOSE. Is the difference between the Desired Exhaust Gas Recirculation (EGR) Valve Position parameter and the Exhaust Gas Recirculation (EGR) Valve Position parameter within the specified range?

Value: -5 to 5 %

Yes

Go to Intermittent conditions of engine.

Refer to "202.Engine 15D.Symptom(4JJ3 with DPD) intermittent conditions of engine".

No

Replace the EGR valve.

Refer to "1.Engine 1H.Aux. Emission Control Devices(4JJ3 with DPD) EGR valve removal".

Refer to "1.Engine 1H.Aux. Emission Control Devices(4JJ3 with DPD) EGR valve installation".

=>Go to Repair verification.

8. Repair verification

1) Clear the DTC with a scan tool.

2) Turn OFF the ignition switch for 1 minute or more.

3) Start the engine.

4) Operate the vehicle under the conditions for running the DTC.

5) Observe the DTC information with a scan tool.

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