Originally posted by SVT-N:
Just wanted to give an update for those that were following this thread a while back...
Well, it's been roughly 2-3 weeks now since I had the stock Y-pipe put back in and so far (knock on wood)
no CEL! So apparently something with the Y-pipe was causing it.
Anyway, I'm happier with it removed. Not only for the CEL, but the volume of the exhaust was just too
much for the long commute I have everyday. However, I do miss the extra pull it gave.
Thanks again for the assistance you all gave,
Jay
Don't jump the gun just yet. It takes a while for the catalyst test to run in OBDII. Also, I know some people have cleard the 420 code and it didn't come back for a couple of months!!!
Hopefully you have solved the problem, but the Y-pipe causing that code does not make any sense to me anyway.
I have thought it over and if the y-pipe was leaking or if the connections were loose, this would cause a 420. The Ford Service Manual states that a leak in the exhaust or a broken exhaust will trip this code.