Code PO401 EGR insufficent flow detected

Have replaced EGR vacuum regulator, verfied that EGR valve holds vacuum, opens and shuts, good vacuum @ the regulator, have voltage @regulator. What am I missing?

Either the DPFE or carbon built up under the EGR valve in the passages.

EGE tube clear in both lines to the DPFE and to the EGR valve. On the DPFE I am showing 5.0 volts on the sig and ref of the harness even when the truck is cold.

DPFE sensor is bad and is a part stocked by most parts stores knowing they are big problem.

had same problem.was dpfe

Either the DPFE or carbon built up under the EGR valve in the passages.
You have to remove the valve to check this.

Turn out to be carbon between egr and throttle body. For which I removed all and cleaned throughly with brake clean and replaced throttle body to intake gasket. Thanks for all the advice.

Glad you gort it fixed. Thanks for the fix reply.