Could someone Please explain a P0401 code to me?.........

My wife's nephew had gotten a P0401 code on his 1999 Escort. I know that it's an insufficient EGR flow detection code, and the mechanic said that it was a bad EGR back pressure sensor. I've never heard of this (there's ALOT of things that Ihaven't heard of though :)).

Have any of you had this code, and could you Please shed some light on it for me?

Thanks in advance!

This Is A Very Common Problem With Fords - It's The Delta Pressure Feedback Egr (dpfe) Sensor - Ford Knows They Are Junk - They Even Released A Recall And Tsb Not To Test The System For This Code Just Replace The Sensor