My van has the 3.8l with 130,000 miles. I had the catalytic converter replaced about 2 months ago by a local exhaust shop because it was clogged, but the P0420 code came back. If I clear the code its back on with in 40 miles. It runs fine but I have noticed it can idle a little rough at times. It is also louder than it should be so it has an exhaust leak somewhere. Could that be the problem? I have also noticed that it no longer uses any oil since having the new cat put on. Is that normal? It use to use about a quart of oil every 1,000 miles or so. I have my inspection coming up soon so I need to figure this out. Any suggestions would be great. Thanks.
Definitely fix the exhaust leak. It can trip the catalytic converter code. Also, check the bank 2 oxygen sensor readings and make sure it works fine. Regarding the oil consumption, it is not related to the cat.
