floatinghat, i jumped on him because he has a common misconception with auto repair, all you need is that damn scanner and it will fix your car, or i looked on the internet and now i know what is wrong....not . more than likely fishrangers truck is setting a p0420 code for a bad cat that was diagnosed by dealer that has a clue what they are doing but charges more than an independent shop so he was looking for advice on where it could get done for less. p0171 and p0174 are fuel system lean codes for each different bank of the motor which are extremely common codes for a ford to get and they are not set by a bad cat, besides he never said he had those codes so where would boone come up with that. oh wait thats right he had those two lean codes and put cats on it that did not fix it, then found a dirty maf sensor that caused his problem to begin with. maybe if he was a mechanic he would have checked that first, i know i would have.