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I own a 2002 C4S Tiptronic with 21,600 miles, and I just found out I have a cracked catalytic converter. Few questions...

1) I have seen 2002 turbo cat on Ebay...Will this work in a C4S?

2) I searched the DIY tutorials....I didn't see any on replacing a cat...is there one for this that I missed? How difficult is the replacement for a novice?

3) Any suggestions on where to look for a used catalytic converter?

Thanks in advance for all responses !

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  • Admin

1. Turbo cats (and engines) are completely different from the 996 M96 engine.

2. Pretty straight forward - cats go between the headers and the muffler. Carefully take the the O2 sensors out first and keep them clean (no oil or liquid wrench). Expect to replace the bolts/nuts on the header side but the muffler side is usually able to be reused. Maybe 1 hour with stubborn bolts and cleanup.

3. Auto salvage yards if you don't mind used. Since you have a 3.6 liter you will need a cat (left of right - they are not interchangeable) from a 3.6 liter 996 or 997-1.

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  • Moderators

I had a similar situation last year with my 2002 996 with 65K miles on it. Depending on what state you live in, the cat may be covered by a 7/70Km emissions warranty. I would talk it over with your dealer and ask them to get Porsche to cover the replacement. Porsche replaced my faulty Cat at no charge.

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The federal emissions warranty is 8/80. I'm on my 5th set of cats, and I have no clue why they're going bad this often. I don't have oil smoke either. Been this way since the car was new.

Now that the car is out of warranty, i'm just going to run without catalytic convertors since they're over $2K.

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Running without cats makes it a little tough to pass emissions isn't it?

true, but the car passed emissions last year, so i'm good to go for a while. I'll see what the problem is but it's abnormal to be going through so many catalytic convertors. Will have to call PCNA again. The last set, changed out at 90k miles (9k miles ago) was done under goodwill by PCNA.

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For sure......But there is absolutely nothing that indicates a symptom for failure. I don't know if they make aftermarket catalytic convertors either that fit. Maybe the cause is that the Porsche ones aren't just meant to be for my car.

I would find the reason way they always break, instead of always replacing, warranty or not, this situation is highly unusual IMHO.

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It is a constant rattle at idle. Scared me because I thought it was in the engine. I took it to an local independent to diagnose it, and he was able to isolate it in the catalytic converter, It is not loose, rattle is from the inside,

Just interested--what are the symptoms? I have heard about a rattle, but not sure if it is a constant rattle or a rattle just when going over bumps.

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thinking about replacing with a fabspeed cat, instead of stock or used. Anybody have any opinions on this?

It is a constant rattle at idle. Scared me because I thought it was in the engine. I took it to an local independent to diagnose it, and he was able to isolate it in the catalytic converter, It is not loose, rattle is from the inside,

Just interested--what are the symptoms? I have heard about a rattle, but not sure if it is a constant rattle or a rattle just when going over bumps.

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I had the exact same problem on my 02 C4S. Replaced with a used set I found for 400.00 with about 1200 miles on them. Basically brand new. Interestingly enough, most of the cat failures I have read about seem to be 02... Makes you wonder if they had a weak batch. No empirical data, just my observations! When I shook mine after removing you could hear the ceramic clunk back and forth. Can't answer your question about the after market cats but I tend to be a bit skeptical about all the gains they claim so I just stuck with the OEM. Trouble free for the last 6K.

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A little hard to tell it sounds more eng internal (lifters etc) then cats. Do you have a CEL light or try hitting cats with rubber mallet with eng off to see? If you could take it in for second option I would.

Edited by Mother
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I went to start my 99 996 C2 this morning and it now has a constant rattle.

It rattles a little on idle but when I apply the gas it rattles even more.

Could this be my cats going bad..never had them replaced and I have 59k miles on her.

I made a mp3 recording of the engine on idle and with gas

996 engine mp3

Thanks

Brian

Yup - sounds like cats. But as everyone has said, with engine off hit the cats with a mallet.

If they make a sound it's for sure.

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  • 1 month later...

I have a set of cats for sale gentlemen - they are off my 2002. I replaced them *thinking* they were the source of a rattle I had at 2000 rpm, but after installing the new cats the rattle/buzz is there exactly as before.

I have since tracked the rattle down to the right side muffler, which is what I should have done to begin with. My car is 98K miles, but a new warranty motor at about 40K miles. Not sure if the exhaust was replaced with the motor or not. I assume they were not.

So the cats are high mileage, but they were quiet and I had no issues passing smog testing. They came off just last week.

I will sell them at a very low cost of course. $250 should do it, and I estimate shipping costs of $50. I will offer a warranty to lower your risk. Install is a snap. It took me less than four hours and that included a trip to the hardware store for penetrating oil and a bit of a wrestle with some rusty nuts.

Let me know...

Jasper

rexjoropo@gmail.com

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