P0401

DTC P0401 EXHAUST GAS RECIRCULATION FLOW INSUFFICIENT DETECTED

Component Location:

COMPONENT LOCATION

GENERAL DESCRIPTION
The Exhaust Gas Recirculation (EGR) system is designed to introduce exhaust gas into the combustion cycle. This lowers combustion temperatures and reduces the formation of oxides of nitrogen. The amount and timing of exhaust gas introduced into the combustion cycle varies by such factors as engine speed, engine vacuum, exhaust system back pressure, coolant temperature and throttle position.

DTC DESCRIPTION
If the pressure change of intake manifold is less than 26 mmHg(AT) when the EGR S/V is operated, the PCM determines that a fault exists and a DTC is stored.

DTC Detecting Condition:

Schematic Diagram:

COMPONENT INSPECTION
1. Check EGR S/V
1. Ignition "OFF"
2. Detach EGR valve.
3. Check EGR valve for sticking or carbon deposit.
4. Apply a vacuum to EGR S/V and check that vacuum is kept hold.
5. Blow air on one side of EGR valve and check that air is not passed through(when a vacuum is not applied).
6. Blow air on one side of EGR valve and check that air is passed through(when the vacuum which operate EGR valve is applied).
7. Attach EGR valve with using a new gasket.




8. Perform EGR actuation Test with Scantool.
9. Is the EGR valve working properly?

YES:
- Substitute with a known - good PCM and check for proper operation.
- If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.

NO:
- Substitute with a known - good EGR Valve and check for proper operation.
- If the problem is corrected, replace EGR Valve and go to "Verification of Vehicle Repair"procedure.

VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs.
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Monitor that all readiness tests have been verified as "Complete"
5. Are any DTCs present?

YES: Go to the applicable troubleshooting procedure.

NO: System is performing to specification at this time.