I have a 2001 Nissan Pathfinder SE 3.5 with 170k on it. I just got it so I don't know the history, but the SES light came on with a code of P0420 and P0430 - Catalyst under efficiency. I noticed a rattle when turning the engine off from the resonators on the driver side an possibly the passenger side. Checked under the truck for loose heat shield, and everything is secure, and no visible cracks in the resonators. Could it be the resonators causing the error codes in conjunction with bad o2 sensors downstream? What would cause the rattle in the resonator (not sure what's "in" those) or why the would deteriorate. The truck gets about 19 mpg still, it runs perfectly, and I haven't noticed any dirty oil or oil consumption, no smoke. Other then this issue the truck seems perfect. I like the looks and the way this truck drives, but I'm thinking I just bought a perfectly good money pit.