fixed P0401 now P0402..
I replaced the DPFE to fix the P0401. no CEL for 500 miles, today get a P0402. I took the egr off again and inspected the pasages and gaskets to the EGR. They were clean and EGR seals fine. I applied vacuum to egr while car is running and it died (good). I checked vacuum to the EVR (EGR valve regulator) and i see 19 hg/in. I ensured the hard plastic line from EVR to EGR holds vaccum (no leaks) Any ideas what could cause this? Is it possible the EGR gaskets are leaking? Excessive flow means what exactly? I know the EGR is not opening at idle as I tested the vacuum source to it. What exactly does excessive flow mean? When is the flow excessive?