My CSVT is throwing a P0420 code as well and say "catalyst efficiency below threshold." My car only has 45k and the service tech at the Ford dealership told me that it is probably a bad precat and is covered by the 8/80,000 emission warranty. My car runs fine, except I think the fuel pump is also going out because it bucks at 5,000 rpms when I only have 1/4 tank or less.
