Thread: how much vacuumn should you have at idle??

P0401 is for the EGR, the EGR is electronic not vacuum actuated.

A code P0401 most likely means one or more of the following has happened:
The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
There is a blockage in the EGR (tube), most likely carbon buildup
The EGR valve is faulty

I would just go to a junkyard and pull off an egr valve if it was me. I would grab the tube as well if you can.