EHarris

Yea this one sucks for sure. I might go down to a local jeep custom shop by me that I've been extremely happy with helping me get out of jams and checking over my vehicle before each summers long trips and see if they are able to help diagnose further with their scan tools if its the CAT or the O2 sensors.

It does appear you can order all of this off Rock. The cat is $800 ($1000 but -$200 core) and the sensors are about $50 a piece for mopar. Maybe about $100 in parts and extras should you need them and I arrive at $1100 with shipping. The EGR Valve is an $160. I feel like if I'm taking the JKU plus 200k I might as well just get this over with now unless diagnostics tell me just O2 sensors. I mean the sensors do have 175k on them and could easily be shot. It's just for some reason I come across a lot of posts where its the CAT and apparently I'm lucky to have made it to 175 with no issues.

I've got 200k in my sights but think I can go further than that for sure. So if you are gonna use it for another 50k lets call it and take it to 225k which is about 3-4 years of more heavy driving was the only reason I arrived at replacing it all since the CAT could go bad within the next 50k most likely? These things don't seem to be lifetime in anyway.

karls10jk

The cats really should be lifetime unless you are dumping fuel at them due to O2 sensors. I'm just not so sure that it's your cats yet. Again, I'm over 215k miles and I'm not easy on it, and the cats were clean when I pulled them. The sensors, I can see replacing them to ensure you're at maximum efficiency. Once I get other things sorted on my Jeep, I'll replace all of my sensors to (hopefully) help with efficiency. 16mpg isn't bad but I think I should be able to do better when I'm putting stock tires back on.

my vote still says sensors before cats. That's just my feeling though.

EHarris

Sensors it is first. Why the hell not. I'll buy the O2 sensor socket tool. Any advice on that one? I'll pull the sensors and start there.

karls10jk

I didn't buy the tool, but I'd refer you to my earlier post with heat cycling with your favorite lubricant. I use kroil but I experiment with everything when it comes to rusty fasteners in a place that won't be easy to get them out......though one could argue that you could pull it to the bench and take a torch to it if they are really seized.

EHarris

Ok I use Kroil and PB blaster. I'll start the lubrication routine so they hopefully come out early. I'll look for the specific socket to make this easier.

Mark Doiron

I've been down this path, both to R&R the clutch, and because of P0430. Pulling the cats was not too bad, though we did have to cut off one of the bolts at the exhaust manifold one time. You should have four new bolts and nutplates for the manifold connection on hand--your old ones will be badly rusted. As for just replacing the O2 sensors: Yeah, if you're not paying labor, try it. Didn't work for me. Ended up having the whole cat replaced a few months later. I figured my cat suffered from the harsh vibrations of washboard roads while overlanding. A bit surprised I got over 200,000 miles out of it.

EHarris

damn this is what i hear from alot of people. I put a can of sea foam in mine over the weekend for a 400 mile trip i did. Vehicle smoothed right out again and the code has yet to come back. I'm thinking the sensors could be good right now but the CAT may not be too far off. I'd have no problem pulling the trigger if the CAT was a little bit cheaper but all I can see is me paying $800 for a cat and $200 for new sensors. I'm searching for a CARB compliant alternative right now.

EHarris

Well I put a can of Sea Foam in the gas and my code has yet to return. It's been about 300 miles. I will keep this post updated but if Im feeling good about it I may try for a quick Smog while its good and then I can take my time.

EHarris

ok code came back on about 500 miles later after a can of sea foam. It kinda has a rough idle to it also while the check engine light is on. Does anyone have the official part numbers for 3.8l (2008 JKU) o2 sensors? Or can someone help identify which mopar ones on Rock? Im slightly confused on the exact upstream and downstream versions.

https://www.rockauto.com/en/catalog/...2)+sensor,5132

MOPAR 56029049AA
MOPAR 56029085AA

MOPAR 56029084AA

I've always put only Mopar sensors in my JKU but Im asking if this is a time to try NTK?

karls10jk

I have the 08 parts manual on my computer, I'll see if I can find it later on. If not, Mr. T may have a copy as well as Ron, they seem to refer to it like I do.

As far as the NTK- I'm under the impression that they're the OEM supplier, much like Bestop supplies the tops and they just put a Mopar logo on them. I went back and forth on this same thing with plug wires- Mopar or Denso. I ordered the Denso from RockAuto and if I were to set them next to my original plug wires, you'd never know which is which. They're the same without the markup for putting it in a Mopar box.