My 2005 Screw with 146K on the clock. Just threw a P0430 code. I had this last summer and replaced the Bank 2 cat with a Magnaflow. I had a exhaust shop weld it in. I just went under the truck with it running to feel around for a leak (hoping) and felt one on top of the rear weld. Could this be giving me the code? As it happens (always) I am due for an emissions test.

 

Yes, exhaust leaks around the cat can trip an efficiency code.