Underbody Catalyst
WARNING: This page is about a different car, the 2011 Mercury Milan, 2011 Lincoln MKZ, 2011 Ford Fusion, 2010 Mercury Milan, and 2010 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
The underbody catalyst is located after the light-off catalyst. The underbody catalyst is in-line with the light-off catalyst. For an exact configuration of the catalyst and exhaust system, refer to the EXHAUST SYSTEM -- FUSION, MILAN & MKZ