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Discussion Starter · #1 ·
Hi. 2007 FJ 4WD w 160k miles error codes P0420 passenger side and P0430 driver side codes came up. Catalyst inefficiency meaning the catalytic converters were no good. Ran cat cleaner through the gas tank and no change. Dealer wanted 4g for new cats including install. I paid $750 total. 2 Eastern Catalytic cats from RockAuto at $250 a piece and 2 Denso air/fuel sensors at $125 a piece. I tried the cheaper UltraPower sensors but their clip didn't fit into the FJ's sensor clip. The job is easy and I will outline it here. Basically it includes taking 6 nuts off the exhaust manifold as it attaches to the engine and two nuts where the exhaust connects to the next rearward exhaust pipe.
 

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Discussion Starter · #3 ·
Soak the 6 exhaust manifold nuts and 2 exhaust tube nuts w a rust loosening agent like PB Blaster overnight. Make sure to get the 3 bolts below the exhaust manifold really well. Harder to get to but don't ignore them. Here I'm showing the nuts on the exhaust manifold and exhaust tube. The nuts on the exhaust manifold are 12mm and for the most part come off easily. FYI they are on bolt posts that are driven into the engine and the nut comes off preferentially. Don't try to take the bolts off w the star bit. It'll likely break off. You'll have to catch the nuts on the underside w ur hand and do it by feel. Put a towel down to prevent them from dropping into the engine. The exhaust tube nuts are 15mm and attached to similar bolt posts that can move. Don't be concerned if u ruin the bolt post bc the new cats come w new post bolts. I sheared mine. If it's really stuck you'll have to cut the bolt off.
 

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Discussion Starter · #4 ·
There are brackets holding the cats in place. Take off the 14mm bolt that attaches the bracket to the cat near the 2 15mm nuts. Take off the closer 14mm nut and u can turn the bracket out of the way. Push or pull w a pry bar really hard and it'll move out of ur way. There is no need to remove the front prop shaft.
 

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Discussion Starter · #7 ·
Remove the 6 12mm nuts holding the exhaust manifold on. There are 3 nuts above and 3 below. I found it easier to use a long socket to reach the lower 3 and finished taking them off by hand to catch them. Don't forget ur towel under them in case they fall down. These nuts are fairly soft metal. If possible, use a multi tooth wrench or socket instead of the standard 6 sided type. U can also use a long socket extension and go through the wheel well.
 

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Discussion Starter · #8 ·
So I said the nut metal was soft. It is. It stripped on the driver forward most lower nut. It was frozen on pretty well. I filed the sides and used a wrench to no avail. Then I tried to remove the bolt post w a star bit and that snapped off so don't try that. Then I used a Dremel w a 1mm burr bit and cut through the nut carefully until I saw a hint of thread. I used a long flat head screwdriver and inserted it into the groove facing left and struck it counterclockwise w a hammer. That worked. Put a new nut on and it held tight later during install.
 

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Discussion Starter · #9 ·
The "O2 sensor" ahead of the cat and mounted to this pipe is actually a air/fuel sensor. The readings do not oscillate like a upstream O2 sensor would on an older truck. Either way, avoid the Ultrapower sensors bc they don't clip into the wiring harness well. A tip in disconnecting the sensor is to go from below the truck and reach up. U can see the sensor clip this way. U have to squeeze the clip release tab which is away from the sensor. My tabs wouldn't squeeze bc they were clogged w dried mud so I soaked tapped em, blew em out w canned air, and soaked em w electronics cleaner and eventually with some wiggling the tab moved but it required a gentle tug on the sensor plug at the same time. Tricky stuff but you'll get it.
 

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Discussion Starter · #10 ·
Now u can pull the cats out. A few points. Wiggle the exhaust manifold outward from the engine. If it's not moving u can gently tap it to break it free. There is a gasket under it which u won't reuse and the Eastern Cats come w a new gasket. FYI, the Eastern Cats fit perfectly and the nuts will be easier to see than stock. Where the cats bolt onto the exhaust, there is a gasket sitting in the exhaust tube. The Cats came w new gaskets but I left mine in and there were no problems. It's a pain to get them out and clean the pipe. I pulled my cats out the bottom sort of in line w the exhaust pipe. Once out, I tried to take the sensors off w a wrench but no go. I soaked em in PB Blaster for a day still no go. So I got a sensor socket from Harbor Freight for $5 and that eventually worked. I put the old sensors on the new cats. Installed everything and there was a lot of smoke from the sensors. Crap. I removed the cats and tightened down the sensors. Reinstalled, same smoke. Crap. Took em out, reamed the sensor hole in the cat w a $5 thread chaser made for sensors again Harbor Freight. Smoked again. Crap. Removed the cats yet again and did a smoke test by closing all holes and blowing smoke in w a smoke gun. No smoke. Figured maybe the smoke from the gun was too weak so I blew in cigar smoke really hard. No leak. WTF? I then remembered I put thread compound on and maybe that was just burning off. That was the case. I let the engine run until the smoke from the sensors disappeared and good to go. 6 removal and installs on each side later.
 

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Anyway, the codes resolved and I though I was good. Next day passed emissions. Christmas tree came back on 2 days later. Crap. Ran the codes and got a EVAP large leak code. Gas cap wasn't clicked in. Resolved. Well it's been 3 weeks and no codes. Drove 1200 miles and no issues. Good luck. I hope this helps. As an aside, I believe my cats went bad bc my valves r dirty. My long term fuel trim was 14%. Now they are 0.0 after using Seafoam in the air intake.
 

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Same problem here. I used magnaflow primary cats. I figure the shorty header design should eek out a little more torque, but I have no data...
 

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Awsome thread! I've got the p0430 on my 07 with about the same miles as you and am tired of just resetting via Torque! I feel like this might be do-able myself with all these picks, thank you so much!
 
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Nice write up. When my cats go bad... I’m off to URD for headers, y-pipe and high tuck. Oh... and o2 baluns to keep the ECU happy.

Alabama does not enforce smog requirements. Loving the south!


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Are they holding up good still?
I am getting P0420 and P0430 codes.

Just bought the FJ about 2 weeks ago. Guy said it needed an 02 sensor.

It's an 07 with 210xxx miles runs well but lights are driving me crazy.

I'm thinking it's the catalytic converters though. Been looking at these.

I got into the FJ cheap so I'm good with replacing them just want to make sure that's what is wrong.

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Great timing with the solution to the problem. Going through the list of possible causes of code 0430 and 0171 and 0174 . Very help full.
 

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Great write up! I just got the codes too. I might have to look at URD....hmmm. Definitely some issues to look out for. I hate soft nuts....wait...that didn't sound right.
 
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