Your programer dosn't have enough code info in it's program.
P0401 code is a common fault code.
It is a low flow failure in an EGR system test.
Get the code read with a scanner and it will tell you the same thing.
Could be any one or more of the following;
1. Blockage behind the EGR valve in the intake manifold.
2. DPFE, it's connection hoses, plugup etc.
3. Blocked metal pipe the DPFE is connected to.
4. Vacuum control regulator or hose between the intake and the EGR valve.
5. Faulty EGR.
The 401 code is a test result.
The test is of a total system operation as set up by PCM routine.
If one part fails, the code is set.
DPFE is only one part so no guarrentee it is the problem if the code and CEL does not go off after 2 drive cycles.
Look at the other 4 items as possibilities if your not lucky.