P0401

P0401-EGR SYSTEM PERFORMANCE





For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

This diagnostic is used to check for low Exhaust Gas Recirculation (EGR) flow conditions. When the EGR valve is open more than 60%, the diagnostic calculates an error based on the commanded and actual EGR position. If the error is too high for a calibrated period of time, the diagnostic fails. This algorithm is not used at areas high on the torque curve. The Powertrain Control Module (PCM) will light the MIL lamp after this monitor runs and fails twice. The PCM will turn off the MIL lamp once the diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
Engine running, coolant temperature above a calibrated threshold, intake manifold temperature above a calibrated threshold, EGR valve is open to a calibrated amount.

- Set Condition:
Commanded versus actual EGR fraction differs by a calibrated threshold.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. CHECK FOR AIR FILTER RESTRICTION

NOTE: Repair any other EGR related DTCs before proceeding.

1. Examine the Air Filter minder.

Is the air filter restriction within allowable limits?

Yes

- Go To 2

No

- Replace the Air Filter.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

2. CHECK FOR INTAKE AIR HEATER RESTRICTION
1. Remove air inlet connection and inspect Intake Air Heater.

Is the Intake Air Heater restricted?

Yes

- Clean area and reassemble.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 3

3. CHECK FOR EGR SYSTEM LEAK
1. Look for visible signs (soot streaks) of an external EGR system leak.

Are there any EGR leaks?

Yes

- Repair the leak in the EGR system.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 4

4. CHECK FOR INTAKE AIR SYSTEM LEAK
1. Check for leaks in the Intake Air System. Perform the INTAKE AIR SYSTEM PRESSURE TEST. Intake Air System Pressure Test

Was an Intake Air System leak found?

Yes

- Repair the Intake Air System leak.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 5

5. CHECK THE THERMOSTAT OUTLET
1. Remove the EGR Outlet Temperature Sensor from the thermostat outlet.

Is the outlet free of debris?

Yes

- Go To 6

No

- Remove debris from outlet.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

6. CHECK FOR EGR COOLER LEAK
1. Verify EGR Cooler is not leaking.
2. Check for coolant in EGR plumbing, engine overheat fault codes, and low coolant level.

Are there signs of an EGR Cooler leak?

Yes

- Replace the EGR Cooler.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 7

7. CHECK FOR EGR CROSSOVER TUBE RESTRICTION
1. Remove EGR Crossover tube from EGR Cooler and EGR Valve.
2. Inspect tube for restriction.

Is the EGR crossover tube restricted?

Yes

- If possible, clean the tube. If not, replace the tube.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Go To 8

8. CHECK FOR EGR COOLER FOULING
1. Remove and clean the EGR Cooler with approved Mopar(R) EGR System cleaner.
2. Reinstall the EGR Cooler.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 75 seconds.
5. Start the engine. It may be necessary to test drive the vehicle.
6. With the scan tool, check for a one trip fault logged against DTC P0401.

Is there a one trip fault logged against DTC P0401?

Yes

- Replace the EGR Cooler.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Test complete.