Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0401
DTC P0401 : EGR Insufficient Flow
NOTE: Before you troubleshoot, review the general troubleshooting information .
| DTC Description | Confirmed DTC | Pending DTC | Freeze Frame |
|---|---|---|---|
| P0401 EGR Insufficient Flow |
DTC (PGM-FI)
- EGR valve check
-1. Turn the vehicle to the ON mode.
-2. Clear the DTC with the HDS.
-3. Start the engine. Hold the engine speed at 3, 000 rpm without load (CVT in P or N, M/T in neutral) until the radiator fan comes on, then let it idle.
-4. Do the EGR TEST with the HDS.
EGR TEST
Is the result OK?
YES
Go to step 2.
NO
- Problem verification:
-1. Test-drive under these conditions:
- Engine coolant temperature (ECT SENSOR 1) above 158 deg. F (70 deg. C)
- CVT in D, M/T in 4th
- Drive the vehicle at a steady speed between 15-75 mph (24-120 km/h) for at least 5 seconds
- Drive the vehicle at a steady speed between 55-75 mph (90-120 km/h) for at least 10 seconds
- During the drive, decelerate (with the throttle fully closed) for 4 seconds
Signal Current conditions Values Unit ECT SENSOR 1 Signal Current conditions Values Unit VEHICLE SPEED -2. Monitor the OBD STATUS for DTC P0401 in the DTCs MENU with the HDS.
DTC Description OBD STATUS P0401 EGR Insufficient Flow Does the HDS indicate FAILED?
YES
Clean the intake manifold EGR port with throttle plate cleaner. Also, clean the passage inside the EGR valve with throttle plate cleaner.
NO
If the HDS indicates PASSED, intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the EGR valve and the PCM. If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot . If the HDS indicates EXECUTING, keep driving until a result comes on. If the HDS indicates OUT OF CONDITION, meet the test condition and recheck.
NO RELATED
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.