Have been getting the ol' P401 code for quite some time on my 1997 4.6L with 180,000 miles. Replaced the EGR valve - that didn't do it. Replaced the DPFE sensor - That didn't do it either. Pulled the TB and cleaned out all the ports. They were packed with carbon so I figured that would do it. That worked for about 2 weeks. Now my CEL is back on with the same code. What next? The EGR position sensor?

 

Code 401 is insufficient flow.
You still have some blockage.
The PCM tests this by detecting flow rate thru a calibrated orfice.
The code will clear by disconnecting the battery and rebooting the computer but the trouble is still there and will show it'self again.

Guys, gotta look at what the codes are saying!
All this info is on the Ford Motorcraft web site under system operations. It's free.

 

Another thing to chack is the vacuum supply to the EGR solenoid, I've gotten stumped on that one my self, if you have no vacuum there check over by the battery, just follow the lines back and see if you have a line off or broken

 

Thanks! I'll try that. The CEL has now gone off and been off for a few days but it's cutting out quite abit especially around 1800 rpm.

 

take a look at this link... i had the same code a year or so ago?

EGR INFO