I have a 99 Prelude SH and my cel has recently kept coming on. I had the code read and it read p0401 "EGR flow insufficient."

At first I thought that my egr ports were clogged so I tried cleaning them out with seafoam. That didn't work so I decided the replace the EGR valve. I paid 200 bucks for a new EGR valve only to have my cel come on a week later.

I don't know what to try anymore. Does anyone out there have a solution for me. Could my EGR ports still be clogged? and if so, how can i clean them out properly?

 

theres a possibility theres a problem in the vsv (vacuum switching valve)
i would check into that next

 

where is the vsv? and how would i check if its working right?