[boomhauer]

first off, i am new to site and mustangs. bought my 1st one 2 days ago and it is a '03 v6 gun metal gray in color.

now, here is a question or 2 and would appreciate any and all help i can get.

1st off, i searched and got no matches so i am asking. does anyone have a diagrahm or exploded view of the stock v6 exhaust set-up or a link to one?

2nd, do the o2 sensors work off of the 2 pre-cats on the 03's or both the front and rear cats?

reason i am asking is that i bought this car knowing the 2 back cats were cut off but 40 miles after i paid for it the cel came on and i am trying to figure what i need to do to fix this. the place i bought it from is willing to get me the 2 back cats if that is what i need but i am thinking i need the front 2 pre-cats. if i remember right, when i looked at it y-day it went like this...manifolds/o2/pre-cat/o2/back cats. am i wrong on this or is that right and the o2's work off of the 2 pre-cats. thank you very much for any help, boomhauer.

btw, the codes were p0420 and p0430

[ClemsonFan21]

If you click on the sticky thread about exhaust you'll find out just about everything you want to know about exhaust. And if you scroll down you'll find the pic that you're look for.

Hope that I helped and welcome to MM

[boomhauer]

i did that before i asked the questions and found nothing i was looking for unless it is in one of the vids. as far as the diagrahm goes i can see where the upstream o2 is (in front of pre-cat) but can't see where the downstream o2 is thus my question as to which of the cats the o2's work off of. thanks, boomhauer.

[walt1120]

Originally Posted by boomhauer i did that before i asked the questions and found nothing i was looking for unless it is in one of the vids. as far as the diagrahm goes i can see where the upstream o2 is (in front of pre-cat) but can't see where the downstream o2 is thus my question as to which of the cats the o2's work off of. thanks, boomhauer.

im almost positive the downstream o2 is in the main cats not the precats. you can buy a MIL eliminator from americanmuscle.com to get rid of the check engine light from taking off your cats. i would leave them off unless your county checks emissions at inspection. oh and the check engine light doesn't hurt your engine at all, the downstream o2 sensors do not affect engine performance. they are basically a way them to know your cats are working at emissions testing