Quote Originally Posted by preferredduck
damn mine is at 180k miles. but as i have read the cat does not gradually go bad it just goes. it ran lean until i found out what the mechanic did and i know that will mess up a cat, and it does it randomly where if the cat was gone it would be a constant thing correct.
I'd say your car has a very lax monitoring strategy for the CAT then. They do gradually go bad over time. The CEL comes on when the catalytic converter's efficiency actually is less than a determined value in the computer. So they can be gradually going bad, but not set the CEL until its to a certain point.

Cat converters are usually a 2-trip logic detection code. Meaning it takes 2 complete drive cycles to run the monitor to check to see if the cat is good. Its possible yours on right on the borderline right now and at times just makes the mark and sometimes come up short. It probably won't hurt your car to drive with it like this, but it will get to a point where the CEL is constant.