Ford P1401 code

My 2001 Ford Taurus has a trouble code p1401. How do you test this sensor? Any help would be helpfull. thanks

Knowing what engine is in your Taurus would help us help you!!
P1401 is an Egr fault, either valve position sensor high input or or
pressure sensor circuit malfunction depending on the system it uses, pretty common system to fail on Fords, Excessive carbon in the throttle body, intake runners etc, vaccum leaks, cracked hoses etc can also cause system failures, I'd need more info about the car, how it runs,
how much mileage, Has the gas mileage taken a drop?

the gas milage has dropped and it has a 3.0 L engine some have told me it is a dpfe sensor not sur hot to test it though.

The dpfe is pretty common failure on fords, requires a vaccum pump and a scanner or a dvom to test it, look for anything obvious like cracks in it or vaccum lines too it, might be worth removing and inspectting it. The computer measures the flow through it so if it's carbonned up or the lines leading to it and from it are then clean them out first, if the throttle body is dirty you can create that code as well. Good chance the dpfe is your problem