I did my searches and learned a lot from you guys, but still would like to know what changed in the exhaust mid year 2000. I have a 2001 XJ missing the converter, need to fix it, and get it inspected.

 

Which converter are you missing... there are up to 3 (depending on your emissions package)? I wasn't aware of any changes to the exhaust systems... *shrug*?

 

Well it looks like there are two canisters welded to the front pipe just after the exhaust manifold. The single traditional converter is missing along with the O2 sensor right in front of the muffler. From what I can tell, there was a mid-2000 change from clamp-on or weld-on to 2 and 3-bolt flanges.

 

yes you have two " pre cats" right after the exhaust manifold. you also have 4 o2's one befor and after on both of them

there is that converter befor the muffler too.. but no o2 on that one the converter is welded in the muffler has a 2 bolt ( i think ) flange

but what is your Q?.. you just want to know the difference?

 

I want to put my exhaust system back to stock and my engine light is on, so I assumed there was an O2 fault because the cat was missing. If there's no O2 sensor behind the rear cat, then the electronics doesn't know that the cat is missing. I wonder why they designed it that way? Anyway, I found a 2001 exhaust system last night and removed the bolt-in cat. I guess I have to stop guessing and take it to the parts store for a free diagnosis.

 

The system with the 2 "precats" on the manifold is the california emissions package. Like said above, you have 4 O2 sensors dealing with these "precats". Then there is the 3rd cat which doesn't have any sensors before or after it. I changed mine out for a highflow one and nothing changed. If this 3rd cat was missing it wouldn't trigger a check engine light. See if you can go to autozone and they will read the code for free. My check engine light went on and it ended up being a bad gas cap that wasn't sealing right.