I just changed my fuel filter and spark plugs on my 01 v6, before pulling the filter off I relieved the pressure in the lines (i first unhooked my fuel pump cutoff switch which didnt work) then after some reading found the fuse for the fuel pump, unhooked it, and started the car a few times and let it run til it died, then took the fuel filter off and replaced it. now my check engine light is on. Anyone know why it would come on after such a simple procedure? The old filter was rediculously dirty if that makes a difference. (i dont know the history of this car as i just got it a couple weeks ago)