obd codes 401&402

my daughter's explorer is showing two codes. po401 egr insufficient flow detected and po402 egr excessive flow detected. help me. where should i start?

95% of the time if you get both codes, it is the DPFE sensor. You may want to look at the wiring to be sure the wires are not touching. But, most of the time it is the DPFE.

I have had some surging and rough running engine the code came back as 402. Would this be the sensor as well? I have gone over the engine compartment vacuum lines and replace most of them.

Thank for any advise

dpfe sensor solved the problem. thanks

Thanks for fix reply. Appreciate it.

When I ask for a DPFE sensor the parts guys (AZ, Napa, etc) are baffled.
Is it only a dealer part?

DPFE is probably only a dealer part / or the aftermarket parts houses refer to them as something else / EGR sensor ETC .
However it is best to go with factory parts especially DPFE sensors , you will probably get a kit from Ford with a new (different looking) sensor and a new wiring connector