Quote:
Originally Posted by chuckm
Just got a P0420 code a couple of days ago and my FE has plummeted to ~33mpg. My gut tells me that it is the O2 sensor ahead of the cat; I figure that one would be used to trim the fuel air mix. Any thoughts?
|
It is most likely your cat. The front O2 sensor likely wouldn't have anything to do with this code being set. The rear O2 being bad could cause this, however since your FE has fallen off significantly as well that would seem to suggest a plugged cat.