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I have a 01 4.0 tj. I have a check engine light staying on with the code for cat converter. Tj runs fine. No missing or sputters. Could this be the o2 sensors making the light code? And which sensors if any? Or what else could it be. Any help greatly appreciated.
 

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If it were the 02 sensor, it would be the rear one, placed on or after the cat. However, the cat is for emissions purposes, and a bad one won't change how your engine runs. If you live in a state that does smog inspections, you might need to replace your cat. If you don't, and you don't care about the environment, don't waste your time & money.
 

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If it were the 02 sensor, it would be the rear one, placed on or after the cat. However, the cat is for emissions purposes, and a bad one won't change how your engine runs. If you live in a state that does smog inspections, you might need to replace your cat. If you don't, and you don't care about the environment, don't waste your time & money.
Well the next time you have to get towed and they tell you its the cat you'll get an idea how bad it can make your engine run. Caused a fire on my Toyota
 

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Yep, quite a disaster for me too. My Jeep started stalling out of nowhere. I would be driving down the street and it would just die. Then it would rev high out of control, I couldn't get out of first gear, I couldn't drive over 40 mph, it was a nightmare. The cat controls the emissions, and if it gets blocked, broken inside, your exhaust backs up into your engine, causing all sorts of problems. The inside of the cat is glass. A shop shook mine and it sounded like a bunch of broken glass. The dealership replaced my O2 sensor, rebuilt my heads, changed tranny fluid, all maintenance for the past three years, $2000.00 and still they didn't figure out it was the cat. Or, did they? Two days later, check engine light back on. Took my car somewhere else, and it was properly repaired. No more problems. I will never trust a dealership after that(Long Beach Jeep). Unless, it is warranty repair. They really try to get the warranty repair money back from you. Bunch of crooks in my book.
 

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Well the next time you have to get towed and they tell you its the cat you'll get an idea how bad it can make your engine run. Caused a fire on my Toyota
Obviously the ceramic breaking up inside your cat and plugging your exhaust is going to cause problems. If you hear it rattling then you should replace it immediately. However, the OP did not mention any rattling or sputtering, so I would not suspect this to be an issue.
 

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Glass can be called as a type of ceramic. Therefore, likewise ceramic can be called a type of glass. Both break easily, are very brittle, shatter when broken, there are chemical differences, but the main difference is that glass is transparent where as cermanics are opaque. But, if you drop a piece of either one, the result will be exactly the same; a million pieces.
 

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Glass can be called as a type of ceramic. Therefore, likewise ceramic can be called a type of glass. Both break easily, are very brittle, shatter when broken, there are chemical differences, but the main difference is that glass is transparent where as cermanics are opaque. But, if you drop a piece of either one, the result will be exactly the same.
I wasn't arguing your statement that the interior had glass or ceramic. I was just clarifying that I know a plugged cat can cause mjaor issues, it just doesn't seem the OP has to worry about them unless he hears the ceramic/glass rattling in the cat :thumb:
 

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I have a 01 4.0 tj. I have a check engine light staying on with the code for cat converter. Tj runs fine. No missing or sputters. Could this be the o2 sensors making the light code? And which sensors if any? Or what else could it be. Any help greatly appreciated.

A quick look to see if your gas cap is not tight also causes the check engine light to come on, but, most likely its the rear O2 sensor, just had to change mine.
 

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The cat will not always make a rattling noise if it goes bad. The cats on my old car never did make a rattling noise. My car just was very rough running. It was missing and the acceleration was poor but the idling was where it was most noticeable.
 

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The cat will not always make a rattling noise if it goes bad. The cats on my old car never did make a rattling noise. My car just was very rough running. It was missing and the acceleration was poor but the idling was where it was most noticeable.
That sounds more like a faulty front o2 sensor, which would be slow to react to changes in the exhaust. This would result in slow feedback to the ecm regarding air/fuel mixture and hinder the ecm's ability to adjust that ratio. But hey, I could be wrong!
 

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I wasn't arguing your statement that the interior had glass or ceramic. I was just clarifying that I know a plugged cat can cause mjaor issues, it just doesn't seem the OP has to worry about them unless he hears the ceramic/glass rattling in the cat :thumb:
My bad, I'm a little sensitive sometimes.:thumb:

But, the cat could be going bad. The O2 sensor could be giving you forewarning as it should. If it is the cat, you will know in time. If you aren't having any performance problems or engine noises, I would give it time, instead of just changing things and spending a lot of money. A little proactive inspection by lightly tapping or shaking the cat may be prudent.
 

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My bad, I'm a little sensitive sometimes.:thumb:

But, the cat could be going bad. The O2 sensor could be giving you forewarning as it should. If it is the cat, you will know in time. If you aren't having any performance problems or engine noises, I would give it time, instead of just changing things and spending a lot of money. A little proactive inspection by lightly tapping or shaking the cat may be prudent.
I disagree. I don't think you should ever just wait and see with your cars health. The O2 sensors aren't that expensive and neither is a decemt cat replacement. The o2 sensors don't look that difficult to get to either. Although I haven't changed mine myself.
 

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Waiting with your cat bad and/or O2 sensor MAY (not will) lead to other problems.
 
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