the catalytic converter is a two part set up. You have the main and then the secondary. As the main catalytic converter failed, the material inside of it crumbled and fell in on its self causing it to clog, as well as bits of the materials being blown by the exhaust into the secondary unit. This is where I'm confused/pissed. OK, so they can not replace the secondary catalytic converter since it was not mentioned in the code produced. However, the dealership did see it to take the secondary catalytic converter and bang the end of the exhaust pipe attached to "dislodge" the particles trapped inside it from the crumbling innards of the main converter so that they could be "poured out" in front of my wife and my self as we watched with less than amused expressions, to which the shop manager explained "Sorry folks that's all we can do since it didn't produce a code for the secondary. I don't recommend the nissan dealer in Lufkin Tx for any of your issues.