Catalytic Converter confusion!
 

Hey everyone!
So I have recently purchased a 1997 XJ6 in mint condition, with 177k miles. Runs great, but recently got the P0430 code (Bank 2/sensor 2 I believe).
Fortunately I had already passed the smog test here in CA about 1 week before this light came on!
I'm not too good with cars but am trying to learn as I go and teach myself to do things myself if at all possible.....
Anyways, I have been reading on here and trying to figure out what is wrong, and it seems like it could be a bad o2 sensor (downstream)? This weekend I'm going to install the 'spacers' on the o2 sensors to see if that corrects the problem (i have read others that have done this with success).
If that does not fix the problem, could it be a bad catalytic converter?
Anyways, I'm always trying to figure on 'worst case' scenario's - and in doing so I was first trying to figure out if I could DIY replace my own cat converter(s), but then as I read, I became really confused because now I don't know how many catalytic converters I have on my car? I have read that I have 2, 4 and 6..... very confusing!
Any information is much appreciated.

Your X300 has two catalysts: in the downpipe from the exhaust manifold and the underfloor catalyst.

Typically P0430 cannot be resolved without a catalyst change. Note that replacement catalysts must be CARB approved for your vehicle. In other words, you cannot just fit a catalyst off the Internet unless it is approved by CARB for use in California.

Thanks NBCat! Just wondering what is CARB? Do most suppliers online note whether they are CARB approved or not? Also do you know if my original cats that are in there now are welded or bolted currently? If bolted, I can probably replace myself, but if welded I will need to have a shop do it

CARB is the California Air Resources Board.

Both catalysts are an integral part of the pipes and are bolted to the manifold and each other.

The catalysts are shown as items 6 and 7 in the drawing.

Hope this helps.

This helps, thank you!

Sorry NBCat, but I'm confused...

Doesn't the USA X300 have four total cats? Two on the downpipes and two underfloor? That's what I've always thought! The 2 cylindrical items on the downpipes, plus the 2 boxy items underfloor after the split.

The 4 O2 sensors are mounted above and below the 2 downpipe cats. Worn out O2 sensors can cause erroneous readings and do not necessarily mean the cats need replacing. But... with that kind of mileage, they might! It also depends on your state's emissions requirements. For instance, in Arizona, if your drive cycle for catalysts hasn't completed and set a P0420 and/or P0430 code yet, and the CEL is not lit, you can still pass.

Let's clear up this confusion.

Yes the x300 has 4 cats as stated by Richard and clearly shown in the diagram, 1 x 1/2 cat in each down pipe and 1 in each pipe under the floor one slightly in front of the other Item 7
I would replace the o2 sensors as you are taking them out to insert spacers, (never heard of that BTW)