P0430 Failed Cat - Confirmed?

[Vtx531]

History for those who haven’t seen my other posts: Car had overheating problem when I bought it which I fixed with a new water pump. Also, had check engine light with lean condition codes which was fixed with a MAF sensor and also secondary issue of the AOS boot having a massive vacuum leak.

Now everything is running great but getting a P0430 code for bank 2 cat. Any idea what exactly might have ruined this? I didn’t think lean running would do this. The AOS was replaced by previous owner, maybe they waited too long to replace it?

Does the Boxster have some kind of weakness with these cats? I see a lot of posts about cat failure. I have a Jeep Wrangler that is about the same age and more miles and the cat is looking perfect according to O2 signal is smooth as could be.

Looks to me like my bank 2 cat is shot and the bank 1 cat is not much better...

[JFP in PA]

The three way cats in these cars are excellent. We have had customers go 200K miles and more without problems. Many times, premature cat issues can be traced to gas quality, and/or aftermarket "tunes".

[Vtx531]

Do you agree the cat is bad? Or is there more diagnosis I need to do with O2 sensors?

Also, I am confused now because I thought the cat that would need to be replaced is the one that is combined with the manifold. Going to buy them off another member on here today but reading another post was saying the threeway cat is the bigger one further downstream? I thought the cat that is the one closer to the muffler end is unmonitored?

[JFP in PA]

Originally Posted by Vtx531

Do you agree the cat is bad? Or is there more diagnosis I need to do with O2 sensors?

Also, I am confused now because I thought the cat that would need to be replaced is the one that is combined with the manifold. Going to buy them off another member on here today but reading another post was saying the threeway cat is the bigger one further downstream? I thought the cat that is the one closer to the muffler end is unmonitored?

Sensors can be checked by testing voltage and continuity.

What year and model is the car?

[Vtx531]

2001 boxster 2.7

I read another one of your posts saying the bolts are almost guaranteed to snap off from the exhaust header - now you’ve got me thinking I should just leave it alone and ignore the CEL

[JFP in PA]

Exhaust bolts that have been on these cars for years are often a pain in the butt to work with. Warming things up with a torch helps, but you need to expect some broken bolts.

[pilot4fn]

Now I got woried... I have same kind of header change ahead in a couple of weeks, but am now concerned why the bolts would almost guaranteed to snap...

Originally Posted by Vtx531

2001 boxster 2.7

I read another one of your posts saying the bolts are almost guaranteed to snap off from the exhaust header - now you’ve got me thinking I should just leave it alone and ignore the CEL

[itsnotanova]

I've always thought that driving with a weak/bad AOS leads to an early death for the cats. Penetrating lube and some heat works pretty good to loosen the bolts up. I also recommend not using an air tool to remove them. You need to take it slow so you can feel if they're not turning. Sometimes tightening the bolt before loosening helps. I've also had to go back and forth a few times.

[pilot4fn]

PErfect. Thanks for the encouragament
I'll do the exhaust swap probably in a couple of weeks whaen time allows... Hopefully the bolts open without too much of hassle.
I have done several engines, including changing exhaust bolts but those previous ones have been steel blocks (not aluminium)e

Originally Posted by itsnotanova

I've always thought that driving with a weak/bad AOS leads to an early death for the cats. Penetrating lube and some heat works pretty good to loosen the bolts up. I also recommend not using an air tool to remove them. You need to take it slow so you can feel if they're not turning. Sometimes tightening the bolt before loosening helps. I've also had to go back and forth a few times.