DTC P0401 Exhaust Gas Recirculation (EGR) Flow Insufficient Detected (4JJ3 without DPD)

1. Engine control system check

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 without DPD) Diagnostic system check-engine controls".

2. Current DTC check

1) Start and completely warm up the engine until the engine coolant temperature reaches 60°C {140°F} or more.

2) Idle the engine for at least 3 minutes while observing the DTC information with a scan tool. Is a DTC set?

Yes

=>Go to EGR components inspection.

Go to Intermittent conditions of engine.

Refer to "202.Engine 15D.Symptom(4JJ3 without DPD) intermittent conditions of engine".

3. 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
Ventilation duct connected to the exhaust tail pipe Remove and inspect again if it is connected.

Yes

Replace the EGR valve.

Refer to "1.Engine 1H.Aux. Emission Control Devices(4JJ3 without DPD) EGR valve removal".

Refer to "1.Engine 1H.Aux. Emission Control Devices(4JJ3 without DPD) EGR valve installation".

=>Go to Repair verification.

Repair or replace as necessary.

=>Go to Repair verification.

4. Repair verification

1) Clear the DTC with a scan tool.

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

3) Start and completely warm up the engine until the engine coolant temperature reaches 60°C {140°F} or more.

4) Perform the EGR Solenoid with a scan tool.

5) While observing the Mass Air Flow (MAF) Sensor parameter on the scan tool, command OPEN/CLOSE of the Desired Exhaust Gas Recirculation (EGR) Valve Position parameter. When the command is set to 0 to 90%, does the Mass Air Flow (MAF) Sensor parameter decrease by at least 0.5 V?

Yes

Observe the DTC information with a scan tool.

=>Go to EGR components inspection.