Got the egr trouble code today. By the looks of it online it could be 3 different issues, an I stuck having to play the guessing game with this one? Or is there a cost effective way I can trouble shoot this? Thanks guys.

99 4.6l
Drives perfectly fine with the engine light on. Drove 70+ miles with no hesitation or issues. Just FYI

 

This should help you. Scroll down for all the info.

https://www.obd-codes.com/p0401

 

Ok, I don't have a proper vacuum pump to test the egr, so I will just remove it and clean it.

 

Took apart the plenum, everything, cleaned everything with electrical cleaner, carb cleaner, I mean everything. Got a tooth brush and all... Cleaned the ports, the truck drives great. No issues, but it's still throwing a code for egr insufficient flow. I found a little bit of water in the egr pressure switch when I took it apart... so do I just move on to the egr and replace it?

 

The ports are hard to see if you don't know exactly where to look, even with the elbow removed (on the 4sixes only). If your sure you cleaned the correct ports, then you need a new DPFE. Perhaps that's what you mean by pressure switch ? Iduno, but it looks like DPFE time.

 

Yes, they were hard to see but I did find them and scraped them clean, and yes I couldn't remember the exact name, but yeah, the DPFE sensor. I will try that next and see what happens! Thanks!

 

It was the sensor, truck was throwing a pending code, I didn't even bother clearing it. Just replaced the part and drove it 10 miles, truck cleared the code itself.