Catalytic Converter Recommendations for 2008 JKU - Code 420

TeamFaust

TeamFaust

Member
2008 JKU with 125,000 miles is throwing PO420 code (Right / Passenger side, yes?) and I need to get it pass emissions testing (in Arizona).

Tried replacing both O2 sensors on that side and all seemed good after I cleared the code until about 90 miles later (when CMU started "reporting" again) and bam code back. I'm guessing Cat replacement time so looking for some input from those that have actually replaced them -- ideally OEM would be great but budget is tight and reviews on a number of Amazon/eBay options look promising ($250-$300 range). I would love to get some input on anyone's experiences / recommendation on any of these.

Also anything else (other than the O2 sensors) that I should do while I'l in there -- I do plan to inspect exhaust manifolds etc for cracks / exhaust leaks as well.

Thanks in advance for your sharing.
 
Get the Magna Flow cats. Magna Flow has done a lot of exhaust system research and their catalytic converters work well. They are not cheap. We installed Magna Flow cats in the Grand Cherokee and the Wrangler. You don’t want to cheap out on catalytic converters.

There’s a way to test for bad converters, but I don’t recall how. You should be able to look it on YouTube. A knowledgeable shop can test your converters.
 
I replaced the cat on my 2010 JKUR with the Magnaflow Direct-fit, easy install, no issues; it now costs $500 more than when I bought mine.

Since you live behind the iron curtain, you have to get a CA/CARB copmliant model for your Jeep $5800 for the full direct fit assembly, only the cats $1,134 each 🤪

May be worth paying a service shop to tell you which cat is bad before replacing it all.
 
jeeeep said:
I replaced the cat on my 2010 JKUR with the Magnaflow Direct-fit, easy install, no issues; it now costs $500 more than when I bought mine.

Since you live behind the iron curtain, you have to get a CA/CARB copmliant model for your Jeep $5800 for the full direct fit assembly, only the cats $1,134 each 🤪

May be worth paying a service shop to tell you which cat is bad before replacing it all.
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Profile says AZ. Should be good without CA compliant.
 
OverlanderJK said:
Profile says AZ. Should be good without CA compliant.
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Yep as Overlander said I’m in AZ (escaped CA a couple years ago).

Will look into the Magna Flow as I have their exhaust and really like it. Still interested in low cost options if any recommendations as a possible short term solution.
 
I used an eBay complete Y pipe assembly. It worked great but probably only put 7k miles on it before the LS swap. I put chep eBay cats on the exhaust that I fabricated for the LS swap also. They have over 10k miles on them now. They can't last as long as an OEM cat but I decided to gamble.

www.ebay.com

Y-Pipe Front Exhaust Catalytic Converter For Jeep Wrangler JK 3.8L 2007-2009 EPA | eBay

Find many great new & used options and get the best deals for Y-Pipe Front Exhaust Catalytic Converter For Jeep Wrangler JK 3.8L 2007-2009 EPA at the best online prices at eBay! Free shipping for many products!
www.ebay.com
 
pvkj454 said:
I used an eBay complete Y pipe assembly. It worked great but probably only put 7k miles on it before the LS swap. I put chep eBay cats on the exhaust that I fabricated for the LS swap also. They have over 10k miles on them now. They can't last as long as an OEM cat but I decided to gamble.

www.ebay.com

Y-Pipe Front Exhaust Catalytic Converter For Jeep Wrangler JK 3.8L 2007-2009 EPA | eBay

Find many great new & used options and get the best deals for Y-Pipe Front Exhaust Catalytic Converter For Jeep Wrangler JK 3.8L 2007-2009 EPA at the best online prices at eBay! Free shipping for many products!
www.ebay.com
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That's cheap!
 
pvkj454 said:
I used an eBay complete Y pipe assembly. It worked great but probably only put 7k miles on it before the LS swap. I put chep eBay cats on the exhaust that I fabricated for the LS swap also. They have over 10k miles on them now. They can't last as long as an OEM cat but I decided to gamble.

www.ebay.com

Y-Pipe Front Exhaust Catalytic Converter For Jeep Wrangler JK 3.8L 2007-2009 EPA | eBay

Find many great new & used options and get the best deals for Y-Pipe Front Exhaust Catalytic Converter For Jeep Wrangler JK 3.8L 2007-2009 EPA at the best online prices at eBay! Free shipping for many products!
www.ebay.com
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That's interesting...fit right in without modifications? Might be an interesting solution to get the emissions done.
 
TeamFaust said:
That's interesting...fit right in without modifications? Might be an interesting solution to get the emissions done.
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Yes it was a direct fit. I also cut the converters off of the old Y pipe and sold them at the scrap yard. The brick was collapsed on the passenger front cat but they took it anyway.
 
Ordered so we'll see what happens, Hopefully can get at it next week. I've also had a slight exhaust leak for years so going to inspect exhaust manifolds to try to pin down location and work that one first then Cat Replacement. 🤞
 
pvkj454 said:
Yes it was a direct fit. I also cut the converters off of the old Y pipe and sold them at the scrap yard. The brick was collapsed on the passenger front cat but they took it anyway.
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Saga Continues...was finally able to to get the ordered Cats in...preceded by new exhaust manifolds (OEMs multiple cracks), valve cover gaskets, and upper oil pan gasket replacements...anyway got these installed, took a little finesing and yes had to drop trans crossmember to remove OEM and get these in just right, ran it out for about a 100 miles to make sure everything reporting properly and BAM engine light. Now codes P0430 and P0420 (both banks). In frustration I stopped by a reputable local shop and was told, "unfortunately because it is a CA car (even though I don't need CA compliant here in AZ) the CA vehicle will not accept the readings from non-CARB cats (they are not strict enough) so it's going to throw the codes unless CARB Compliant Cats installed!!! So, won't pass emissions test because computer won't accept the readings, and thus I can't register. 🤬

Now back to the drawing board to try to find some type of CARB Cats that I can afford, if such an animal even exists...prices I've seen are stupid high (the MagnaFlow CARB Compliant ones are $5,000). Jeep back in the garage 😞
 
TeamFaust said:
Saga Continues...was finally able to to get the ordered Cats in...preceded by new exhaust manifolds (OEMs multiple cracks), valve cover gaskets, and upper oil pan gasket replacements...anyway got these installed, took a little finesing and yes had to drop trans crossmember to remove OEM and get these in just right, ran it out for about a 100 miles to make sure everything reporting properly and BAM engine light. Now codes P0430 and P0420 (both banks). In frustration I stopped by a reputable local shop and was told, "unfortunately because it is a CA car (even though I don't need CA compliant here in AZ) the CA vehicle will not accept the readings from non-CARB cats (they are not strict enough) so it's going to throw the codes unless CARB Compliant Cats installed!!! So, won't pass emissions test because computer won't accept the readings, and thus I can't register. 🤬

Now back to the drawing board to try to find some type of CARB Cats that I can afford, if such an animal even exists...prices I've seen are stupid high (the MagnaFlow CARB Compliant ones are $5,000). Jeep back in the garage 😞
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damn, no way to reprogram the ECU get a non-commifornia ECU programmed for America?
or salvage yard CARB cat
 
FWIW I have a friend that lives in Ca. I live in Oregon. I purchased Amazon “Autosaver88” direct fit stainless steel EPA compliant catalytic converters that I ended up not needing and gave them to him. I believe he did some things to make them look old for visual purposes. No codes. Passed smog. In my own experience I have had aftermarket 02 sensors give me trouble. All 4 mopar sensors did the trick. 2 cents 🤷‍♂️
 
jeeeep said:
damn, no way to reprogram the ECU get a non-commifornia ECU programmed for America?
or salvage yard CARB cat
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Did a precursory online search and I don't even see a Mopar CARB option, just the MagnaFlow at $5,800 -- that's crazy and not something I can afford.

Per the guy I talked with there is no way to adjust/reprogram the ECU ( I am sure there is some car computer guru somewhere that could, but I don't know him/her ;) ) ... Looking into trying to find a salvage yard / pick-n-pull / exhaust shop that might have access to a low mileage set of CA cats. Really a bummer because its running great and I'm certain that it more than exceeds the emissions output here if you were to do the tailpipe test.
 
A.J. said:
FWIW I have a friend that lives in Ca. I live in Oregon. I purchased Amazon “Autosaver88” direct fit stainless steel EPA compliant catalytic converters that I ended up not needing and gave them to him. I believe he did some things to make them look old for visual purposes. No codes. Passed smog. In my own experience I have had aftermarket 02 sensors give me trouble. All 4 mopar sensors did the trick. 2 cents 🤷‍♂️
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Interesting...they don't even look at anything, just plug in the OBD II and whatever it reads is what it reads. All areas (Cats / EVAP/ etc) must be "reporting" to/from ECU (sometimes it take 100 miles or so for the Cat Banks to be "reporting") and once they do if they trigger check engine (P0430 or P0420) they won't even test it.. or will fail it. Joping I can locate a salvage yard unit 🤞
 
TeamFaust said:
Interesting...they don't even look at anything, just plug in the OBD II and whatever it reads is what it reads. All areas (Cats / EVAP/ etc) must be "reporting" to/from ECU (sometimes it take 100 miles or so for the Cat Banks to be "reporting") and once they do if they trigger check engine (P0430 or P0420) they won't even test it.. or will fail it. Joping I can locate a salvage yard unit 🤞
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If the code/s are for sensor 1 on each bank you likely have an exhaust leak. Sensor 2 on each bank is catalyst efficiency. If you have Jscan you can monitor fuel trims as you drive. Might help with diagnosing any other problems. For some reason it sticks in my head there was some difference for 10-11 vehicles vs 07-09 even though they were the same 3.8l I’m curious now. Let me look some stuff up and I’ll report back.
 
The mopar sensors are different part#s for 07-09 vs 10-11. 07-09 have 2 different upstream sensors part #’s and 1 part # for both downstream sensors. 10-11 have 2 part#s upstream and downstream.
I don’t know if it is a different reading or just a fitment difference but they are different part #’s I remember going through this when I did the Hemi swap as well. I assumed they were all the same. I kept getting a cat efficiency code with brand new cats. Went and got the correct mopar ones and it went away. Just my experience. Not saying it will work for you. I am hopeful though that you will get it worked out. Emissions is a PITA.
 
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