Question on Engine Code

We are try to figure out what would cause the computer to throw this code, Insufficient EGR Flow on a 4.3 S-10, Thinkin it might me Carbon if you know please help.

whats hte code number? also what year/trans s10?

01 Auto, Code number is P-0401

DTC P0401 Exhaust Gas Recirculation (EGR) Flow Insufficient
id check to see if the egr tube is clogged or its just not working at all. converter could be culprit to.

check the pintle in the egr valve to see if its stuck or if there is carbon keeping it open. Also when the valve is off get someone to start it up to make sure you have good vacuum if the engine revs up high you have good vacuum and i would replace the valve.