1999 expedition p1401

i had my exp scanned at advance and it told me it was a auxillary emissions system.so i scanned it with another scanner and it is giving code p1401 does anyone know what it is.if i clear the code it will not come back on till i shut the truck off and restart it

Possibly the DPFE sensor. Ford is famous for those failing. Also, clean the 2 passages under the EGR valve really good. If there is carbon built up in there, the code can set.