P420 Catalytic converter replacement help - Jeep Wrangler Forum

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Old 01-21-2010, 03:29 PM   #1
Join Date: Jan 2010
Posts: 1
P420 Catalytic converter replacement help

ve been lurking for a while, but finally have a question ive had some trouble answering on my own.

I have a 2000 Wrangler Sport 6Cyl with 105k on it. It spit out a P420 code recently and know that means that the cat is done for. I took it to my local shop in Maryland and they said it was going to be 1800 to fix it with parts and labor. I would really, REALLY not like to pay close to 2k for this and wanted to see if this was something i could do on my own. I came up with a few questions and wanted to see first and foremost if this is a doable job - (im good with my hands but all ive really done is rotate tires and change my own oil). Thoughts?

I found Eastern
Eastern Catalytic Converter Direct OE replacement
on another post in the forum but for another year and wanted to see if this would work. I also dont know if i need to replace the O2 sensor as well with this replacement or if i can use the old one.

I am not really in a rush and dont have emissions coming up or anything, but i would like to see if any of the above would work. Any help or advice you can give me would be GREATLY appreciated.


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Old 05-16-2010, 12:28 AM   #2
Join Date: May 2010
Location: New York City
Posts: 2
Damn Brother... that much for a replacement of a Cat? I have the same problem on my 2000 sport and would like to replace it myslef.

I have found that maybe the slide plate on the under carrige might be in the way for me to see how bad the job would be. I have priced out the Cats for our jeeps from $69 ll the way up to $115.00 on a google search.

Searching around a bit I have foudn that the Cats on the jeeps are fairly cheap, but the expensive thing is on the welding of the pipes if nessesary.

Check out WikiAnswers - How do you replace the catalytic converter on a Jeep Wrangler

for more info.


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Old 05-16-2010, 01:03 AM   #3
Senior Member
Join Date: Sep 2008
Posts: 2,775
It may be likely that the cat is shot with the age and amount of miles on your jeep but that code does not mean that it IS the cat.

Could be an exhaust leak or a bad O2 sensor also.

If the senors are stock (and you'd have to replace them anyway) try to troubleshoot and replace them to see if that solves it and check for leaks too.

Much cheaper than (the total rip off price of 1800 you were quoted) replacing the cat.
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Old 05-16-2010, 01:05 AM   #4
Abe Froman

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Location: Was in the mountains, now in Texas
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Had a cat replaced for 250 and it was a high flow one. Find another muffler shop.
2000 Sahara, 3.5" Rubicon Express Lift, 1" spring spacer & 1" Body Lift, 33" or 35" BFG Mud tires, Front & Rear ARB, Rancho 9000 shocks, UCF Ultra High Belly Up

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Old 05-16-2010, 04:11 AM   #5
Join Date: Aug 2008
Posts: 2,473
Find another muffler shop - not a chain like Midas or Pep Boys. Find a small independent one that other shops near it recommend.

The small dual cats from a dealer are about $700 - but there is not much to go wrong. It would take an awful lot of crud to plug one up.

The big one may go as high as $200. It's just a standard CAT, nothing trick about it.

Even if you needed both, 700+200+labor, it's a far cry from 2K.

And before replacing anything - reset the computer back to default. No matter what others say, there's really only 2 ways you can do it.
1. Use the Chrysler DRB III diagnostic device - not sure of the price but over $10,000.
or -
2. Disconnect the battery for at least 12 hours.

To me, #2 makes more sense.

Clearing codes with a scanner only clears codes, it does not return the computer to default.
There are lots of rumors how to clear the memory quickly - some partially work, most only clear the codes but do not reset the internals. You want it ALL reset.

After the 12 hours, reconnect, then you need to drive it for about 20 miles - drive it easy for the first few miles, then faster and harder. It has to re-learn everything.
A scanner at first will tell you that the battery was disconnected - then as more and more portals open up, it will show any faults that exist. It can take as long as 100 miles before all the portals have opened and it's back to normal.

CATs fail in 2 ways - plugged - due to overheating from a misfire. A vacuum gauge will tell you if it is plugged, not the computer. An infrared laser type thermometer works even better to find a plugged cat.

Guts blown out - The computer detects there's too much O2 getting to the downstream O2 sensor - an exhaust leak or a bad O2 sensor can do the same.

Why are you suspecting a CAT problem?
It's no wonder the country is falling apart - stupidity abounds!
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