To Catalytic Converter, or not to?
Thread Starter
Junior Member
Joined: Mar 2020
Posts: 57
Likes: 1
From: Oregon
Year: 1996
Model: Cherokee (XJ)
I need to decide what to do about my CC/420 code (o2 sensors have been ruled out).
I deliver mail in my '96. An aftermarket CC was installed a little over a year ago, and it has failed. Lots of people I talk to, including a mechanic I trust 90%, say you can't get one from the factory anymore, and the aftermarket ones are garbage. My aftermarket one certainly was, lasting only a year.
The Jeep is running great, but I get to stare at my Check Engine Light all day. The only code I have is the 420 one. I'm not really cut out to not give a damn and drive it around with the CEL on and not worry about it. So what are my options? Please assume the CC is the actual problem. And no, I don't want to pull the bulb for the CEL, lol. I'd like the CEL to still have meaning.
What's going on in the computer while I drive around with this code? How is it affecting my fuel efficiency? Can the CC be deleted and the error code somehow be disabled? Does anyone besides Flowmaster offer a warranty on new CCs?
I am in Oregon.
Thanks for any insight.
I deliver mail in my '96. An aftermarket CC was installed a little over a year ago, and it has failed. Lots of people I talk to, including a mechanic I trust 90%, say you can't get one from the factory anymore, and the aftermarket ones are garbage. My aftermarket one certainly was, lasting only a year.
The Jeep is running great, but I get to stare at my Check Engine Light all day. The only code I have is the 420 one. I'm not really cut out to not give a damn and drive it around with the CEL on and not worry about it. So what are my options? Please assume the CC is the actual problem. And no, I don't want to pull the bulb for the CEL, lol. I'd like the CEL to still have meaning.
What's going on in the computer while I drive around with this code? How is it affecting my fuel efficiency? Can the CC be deleted and the error code somehow be disabled? Does anyone besides Flowmaster offer a warranty on new CCs?
I am in Oregon.
Thanks for any insight.
CF Veteran




Joined: Jan 2014
Posts: 1,543
Likes: 351
From: District of Columbia
Year: 1998
Model: Cherokee (XJ)
Engine: 4.0
You live in Oregon and your code is 420? Story checks out.
I don't have much to offer other than to say I get the impression aftermarket cats are all crap unless you go with one of the expensive ones from a credible performance company.
I don't have much to offer other than to say I get the impression aftermarket cats are all crap unless you go with one of the expensive ones from a credible performance company.
Last edited by IJM; Aug 3, 2021 at 09:06 PM.
Thread Starter
Junior Member
Joined: Mar 2020
Posts: 57
Likes: 1
From: Oregon
Year: 1996
Model: Cherokee (XJ)
I don't mind an expensive one, as long as it lasts. Come to think of it, I don't really know what the life expectancy of a factory CC is anyway.
CF Veteran




Joined: May 2012
Posts: 7,965
Likes: 964
From: Lost in the wilds of Virginia
Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
Well, you have a 96, so the only thing that code is doing is to tell you to fix your cat. The data from the rear O2 sensor is not used by the PCM for running the engines. (There's a sticky at the top of the forum about it. I hear the fella who wrote it up is kinda dumb,and really ugly, but despite that, he got it right by reading it straight out of the factory service manual.)
The later models did use the rear O2 sensor(s) to manage the fuel, so it's a bit more complicated. I'm not sure yet what year switched over, but I know my 97 wasn't using the rear for engine management. I suspect they switched when they went to the coil pack waste spark ignition.
Anyway, it's not a problem on your 96.
As to making the CEL go out, well, I like your thinking. Makes life a little tougher than the "I don't care" crowd, but I like it. Maybe there is an electronic method to fool the PCM. Find out what a good cat looks like to the PCM, and mimic it.
I did a quick search and found a few options:
http://www.colorado4x4.org/vbb/showt...-sensor-bypass
https://duckduckgo.com/?t=ffsb&q=mim...=v171-1&ia=web
The later models did use the rear O2 sensor(s) to manage the fuel, so it's a bit more complicated. I'm not sure yet what year switched over, but I know my 97 wasn't using the rear for engine management. I suspect they switched when they went to the coil pack waste spark ignition.
Anyway, it's not a problem on your 96.
As to making the CEL go out, well, I like your thinking. Makes life a little tougher than the "I don't care" crowd, but I like it. Maybe there is an electronic method to fool the PCM. Find out what a good cat looks like to the PCM, and mimic it.
I did a quick search and found a few options:
http://www.colorado4x4.org/vbb/showt...-sensor-bypass
https://duckduckgo.com/?t=ffsb&q=mim...=v171-1&ia=web
CF Veteran




Joined: May 2012
Posts: 7,965
Likes: 964
From: Lost in the wilds of Virginia
Year: 1998 Classic (I'll get it running soon....) and 02 Grand
Model: Cherokee (XJ)
Engine: 4.0
A LOT more. My BIL just got quoted about 2 grand to do the two cats on his F-150. It's insane.
Senior Member

Joined: Jul 2011
Posts: 560
Likes: 26
From: West Covina, Ca.
Year: 1988
Model: Cherokee
Engine: 4.0
Note from DJ
I had a new cat installed on my 88 Cherokee on 7-18 -19 for $297.55 because the SPOG Police decided that I needed a new one; because the cat had been on the Jeep sense 8-1-03 and was still passing smog test but it no longer had the right code numbers for their liking!
I had a new cat installed on my 88 Cherokee on 7-18 -19 for $297.55 because the SPOG Police decided that I needed a new one; because the cat had been on the Jeep sense 8-1-03 and was still passing smog test but it no longer had the right code numbers for their liking!
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Senior Member
Joined: Aug 2020
Posts: 614
Likes: 205
From: Prescott, AZ
Year: 1988
Model: Cherokee (XJ)
Engine: 4.0
I put stainless steel magnaflow cats from Jegs on my Subaru several years ago. I think it was close to $700 for the pair. They fit correctly and have worked very well for more than 50k. If they make a direct fit for your Jeep I would trust them.
Seasoned Member
Joined: Sep 2019
Posts: 328
Likes: 94
From: Around the world
Year: 2001 / 1999
Model: Cherokee (XJ)
Engine: Fire breathing 4 point Oh!!!
I put a Magnaflow on my 2001 XJ. I didn't think the price was too bad. Contact " Kolak Off-road " I think he can be found on Facebook. He has an AOL address, if you look around on the internet. Another option, if the Jeep was for off road use, would be to install an O2 Bung Extendor.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,579
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
::CF Administrator::





Joined: Feb 2011
Posts: 14,479
Likes: 805
From: Blunt, South Dakota
Year: 97
Model: Cherokee (XJ)
Engine: 4.6 stroker
I replaced my CC a couple of years back, was still in California at the time, I ended up getting a Walker direct fit CARB certified replacement. At that time, I spent around $230, bought it off Amazon. That same part is now over $400 on Amazon.
Luckily for you, since you live in Oregon, you don't need the CARB stamp on your CC....I have run my cat on a stroked motor for several years now, and no complaints. Here's a link to one that's not CARB compliant, notice the difference in price...
https://www.google.com/search?q=walk...obile&ie=UTF-8
The ONLY difference between the two? One has the stamp, one doesn't.
What a racket.
One more reason I don't miss Kommiefornia.
Luckily for you, since you live in Oregon, you don't need the CARB stamp on your CC....I have run my cat on a stroked motor for several years now, and no complaints. Here's a link to one that's not CARB compliant, notice the difference in price...
https://www.google.com/search?q=walk...obile&ie=UTF-8
The ONLY difference between the two? One has the stamp, one doesn't.
What a racket.
One more reason I don't miss Kommiefornia.
Last edited by Rogue4x4; Aug 4, 2021 at 09:25 AM.
CF Veteran


Joined: Dec 2017
Posts: 1,527
Likes: 412
From: San Mateo, CA
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0 Renix, stock.
I need to decide what to do about my CC/420 code (o2 sensors have been ruled out).
I deliver mail in my '96. An aftermarket CC was installed a little over a year ago, and it has failed. Lots of people I talk to, including a mechanic I trust 90%, say you can't get one from the factory anymore, and the aftermarket ones are garbage. My aftermarket one certainly was, lasting only a year.
The Jeep is running great, but I get to stare at my Check Engine Light all day. The only code I have is the 420 one. I'm not really cut out to not give a damn and drive it around with the CEL on and not worry about it. So what are my options? Please assume the CC is the actual problem. And no, I don't want to pull the bulb for the CEL, lol. I'd like the CEL to still have meaning.
What's going on in the computer while I drive around with this code? How is it affecting my fuel efficiency? Can the CC be deleted and the error code somehow be disabled? Does anyone besides Flowmaster offer a warranty on new CCs?
I am in Oregon.
Thanks for any insight.
I deliver mail in my '96. An aftermarket CC was installed a little over a year ago, and it has failed. Lots of people I talk to, including a mechanic I trust 90%, say you can't get one from the factory anymore, and the aftermarket ones are garbage. My aftermarket one certainly was, lasting only a year.
The Jeep is running great, but I get to stare at my Check Engine Light all day. The only code I have is the 420 one. I'm not really cut out to not give a damn and drive it around with the CEL on and not worry about it. So what are my options? Please assume the CC is the actual problem. And no, I don't want to pull the bulb for the CEL, lol. I'd like the CEL to still have meaning.
What's going on in the computer while I drive around with this code? How is it affecting my fuel efficiency? Can the CC be deleted and the error code somehow be disabled? Does anyone besides Flowmaster offer a warranty on new CCs?
I am in Oregon.
Thanks for any insight.
::CF Administrator::





Joined: Feb 2011
Posts: 14,479
Likes: 805
From: Blunt, South Dakota
Year: 97
Model: Cherokee (XJ)
Engine: 4.6 stroker


