Posted 28 November 2012 - 11:21 PM
How old is your Fusion? DPFs were introduced in 2010, so if yours is older then it most likely will not have one. (I also assume it is diesel, yes?)
DPFs need replaced/cleaned out when they get clogged full of soot. If you have one then you'll get a warning light telling you it needs fixed. They do clean themselves, but the warning light must not be on for this to happen. Regen cycles as the process is called, requires a lot of heat so cars with DPFs need taken for a motorway blast every so often.