Hi guys. I went this afternoon to Advance Auto to get my check engine light code read for my 2000 ranger xl. It came up PO401, egr flow insufficient. I don't even know where the egr valve is, so please excuse my ignorance. 3.0 Liter, 4x4, 5 speed manual, if it matters. Pics would be great. I really need to pick up a Haynes repair manual.
:8)Any and all help is greatly appreicated. Thanks in advance.

It could be several things but it is almost always the DPFE sensor or the hoses going to it.

http://www.rangerpowersports.com/forum/showthread.php?t=180892

Yea, DPFE failure is very common when that code comes up, and its generally fairly easy to replace.

While troubleshooting this problem on Saturday, I found one of the hoses going to the DPFE sensor was split right where it goes onto the hose nipple. I didn't realize that this was the much talked about DPFE sensor, but it bolts to the upper intake on the left side of the throttle body. I cut off this bad hose section, and put the hose back on. Disconnected the battery for a while, then hooked it back up. The CEL went off for about 80 miles or so, then back on again this afternoon. I'll have to see if I can pick this up locally. Thanks again.

I stopped by NAPA after work today, and picked up a new DPFE sensor. $68 + tax. BTW, they didn't stock one for the 4.0 engines, only 3.0. Also got the appropriate vacuum hoses and replaced them too while I was at it. We'll see if this fixes my CEL. So far, so good. Hopefully, it will.