Welcome to JustAnswer.com! My name is DriveFast71(Ron) and I will do my best to answer all of your questions completely and accurately.
The most common problem associated with the P0401 is a fault in the DPFE Sensor. Inspect the 2 rubber hose at the bottom of the sensor for any crack, holes, or disconnections. Inspect the electrical connector for any loose, broken or rubbed through wires. If the visual inspection checks ok, suspect a faulty DPFE Sensor. Very common fail item.
The only other component in the EGR system is the EGR Vacuum Solenoid Regulator. If this is not the problem either, it has to be in a vacuum line somewhere. There are only 3 components that when faulty will set a P0401 - EGR Valve, DPFE, and/or Vacuum Solenoid.
Attachments are only available to registered users.