I know you were just trying to help, but please don't post links to other forums as it's against the rules. What you can do though is if you can capture a screen shot of the info you wanted to post, you are welcome to do that and post it here.
Sorry about that and thanks for editing it out. There is too much info to copy here, which is why I tried to reference a few of my sources, but I'll try.
To the OP: Here is a a high-level write-up by Mark Doiron. I had a P0404, not his 406, but the fix addressed my problem as well.
If you've experienced DTC P0406 (and probably others, as well), then you may have a bad EGR valve. This happened to me at about 30K miles. Although it should have been warranted, the dealer kept clearing the code and it would stay away for a few weeks, then return. Long story, short: After 50K I decided to fix if once and for all. Then I read how difficult it is to do. Basically, the service manual has you do this repair from the top of the engine compartment. TORN and I were looking at it and he suggested I remove the passenger-side fender to gain better access. I did and what a difference that made! So, here's what you need to know to do that repair:
1. Remove the fender. It is held on by five bolts, plus eight molding fasteners. The molding fasteners are very brittle, and cost $4.80 at my dealership (each!) to replace. They are AuVeCo part number 20887, and you can pick up 15 for about twelve bucks. So, buy a box of these before you get started (I didn't and my fender is setting in the garage awaiting reinstall in a few days. LOL). Before pulling the fender away, be sure to remove the marker light (one-quarter turn and pull) and set it where it will be out of the way.
2. You really want a very short stool to sit on while doing the repair (8" height or so). You may want to remove the tire before removing the fender, and that will provide a little more access. But, I didn't do it that way and didn't feel terribly hampered (except I could have probably saved a few more of those molding fasteners!).
3. Remove the two 8-mm screws. These are easily accessible by a 1/4" drive ratchet with a 6" extension. These screws were not very tight and, in fact, I had mud on the mating surface of the gasket and the valve (which made me wonder if this wasn't really the problem with the system). The gasket should just fall out.
4. Remove the two 10-mm screws. I used a 3/8" ratchet and a breaker bar--these screws were too tight to loosen up with a shorter handle. And, the hidden one is actually not very far hidden--feel back there with your fingers and you'll know exactly where to place your socket. Also, I felt more confident when I could get a six point socket on this hardware--I surely didn't want to strip a head, especially on that hidden one. Also, for the front one, clearance was about right with a deep socket and no extension, even though a deep socket is not otherwise required for the task (it was just the right length, a smidgen shorter than a short socket and extension).
5. The EGR valve is now loose. Rotate it around and examine the connector. It is very similar to the door connectors--a red tab unlocks it, then pressing just behind the red tab on the black plastic pushes up and allows connector separation. Mine was muddy and didn't want to move. I soaked it in WD-40 and it came right apart. I did have to push the two connector halves together to release back-pressure on the tab so that I could push it down, then pull it back the opposite direction to separate the two. BTW: You're doing all of this with one hand. If you have large hands, good luck!
6. Remove the old EGR Valve and reverse the steps to install the new one. I made sure to wipe off the gasket mating surfaces very carefully. And I noted that the one facing away from me, that's held by two 8-mm screws, had a very rough texture not unlike the side of it that you see in the image above (I checked it over closely with an inspection mirror). It seemed rather odd considering that the other half, on the EGR valve itself, is nicely machined.
7. Once you've got everything all zipped back up, clear your DTC codes (otherwise, you'll have to wait for a period of time for the JK to figure out that it's been fixed--some number of starts or some such), and take it for a test drive. I immediately noted the difference: Where before the acceleration was rough, especially at low RPMs, that was immediately cleaned up. The acceleration is now very smooth, like when new.
8. Parts you've replaced include the EGR valve, two 10-mm bolts and the metal gasket (comes in one kit), and the fabric gasket (order separately). I ordered my parts from Wyckoff.com and saved quite a bit of money over the dealer. And, my local auto parts stores had a listing for the part, but weren't able to get it.
I hope you find this helpful!
Last edited by Mark Doiron; 10-21-2014 at 05:26 PM. Reason: Added into about auto's.
