While searching for a vacuum leak I discovered the riser tube from the exhaust manifold to the EGR Valve had a large portion of it rusted away.
I removed the riser and it looks like the end of the EGR pipe that goes into the exhaust, threads onto a bushing (female thread on the EGR Pipe) then the bushing, (male thread) into the exhaust.

Is the bushing a standard pipe bushing? It looks a lot like a 3/8 to 1/2 adapter.

Secondly, would the hole in the EGR Pipe throw the P0401 code?
I also found the vac line from the valve cover to the throttle body was shot and replaced it. I assume this being a vacuum line leak after the MAF it would also throw the P0401 code too. Am I assuming correctly?
Thank you
Jim

 

As an update. It appears the fitting between the EGR tube and the exhaust IS NOT a standard pipe fitting. The part that threads into the exhaust manifold is not standard pipe thread. And the replacement "Dorman" part is not an exact fit and will need considerable tweaking to fit.
The fitting is ordered and will be in Monday. Time to tweak the riser tube.
Jim

 

I ended up salvaging the fitting off the rusted out EGR Pipe. A dremel cut off the old flare nut and a small file dressed up the threads and the the bench grinder cleaned up the flats. After much tweeking I finally got the pipe in and the flares square. For a tip, I mounted the body of the old removed EGR Valve onto EGR pipe and with other end on the exhaust manifold made the final adjustments. Then replaced the EGR Valve body with the new EGR onto the pipe and then bolted the EGR valve to the throttle body drawing up the bilts slowly and evenly.