Hey guys, I have a 2006 Ford F150 4.6l and about a year ago I completely redid my exhaust, Magnaflow cats 94136,Magnaflow X-pipe, No mufflers and dual 4in tips, everything is 2.5in diameter, the exhaust sounds great and truck feels much better, but recently I've been getting the P0420 code, and the weird thing about it is that it will come and go, sometimes it will stay and ill clear it with aeroforce guages, but I'm at loss here as too what it could be, any one else have this problem or know whats causing it?

Thanks guys for any info or advice!

 

Bump anyone?

 

Bump

 

I had the same problem, A year after having the 94106's i had that code plus the p0430. I would first check for an exhaust leak. If you dont have a leak get a non-foulers to trick the o2 sensor. Thats what I did 8 months ago and code has yet to show back up.

 

Double and triple check for leaks around the downstream o2 bungs and the welds. If you have had any kind of a misfire for any length of time than a burnt cat could be an issue. I THINK p0420 is passenger side (being lazy atm) so make sure you know which side the issue is on and thoroughly check connections and piping. Otherwise research the GOTTS o2 mod and you should be good to go.

 

Yup probably leaks... do what AZ said. I'm getting rid of mine for different cats all together... gotten worse and worse and now it's both banks. It's it worse in the cold (as mine started off, now it's all the time) it's leaks.