CAT converter question

May seem like a silly question, but how do I know if my CAT converter has gone south on me.

I was on a long trip up north, running about 70 mph for five hours. When I pulled in to a service centre for a fill up, the CAT was smoking.

The engine idles fine and the gas mileage has actually improved considerably.

Did the damn thing melt down or what? Why was it smoking?

Any help would be appreciated.

you could possibly be leaking a fluid onto the cat. even if there is never a puddle under your jeep it could all be burning off on the cat

After I greased the crap out of my U-joint nearest to the t-case, I noticed that my cat would start to smell and smoke. Turns out the driveshaft spinning as i drove whipped it all out.

it's either ujoint grease, as was said, or my guess would be the slip yoke seal on the TC is leaking, it slings the fluid around in a circle.

When mine went bad it started making a really weird rattling noise, usually when I was idling or first started moving. I never saw it smoke, You didn't drive through a puddle of something at the station and splash it up on the cat right before you stopped did you? If it had really started to go south I doubt you would be running as good as you are though.

Ha first mod i did when i get my jeep was to take out the cat and weld ina strait pipe muhahahaaha shhhhhh dont tell no one