Well, on the way home today my check engine light comes on, when I got home I hooked the scanner up to the truck and it came up a P0420, my book says this is a "catalyst efficiency below threshold (bank 1)" Could someone explain this to me? Is it a catalytic convertor or a oxygen sensor? I am a little confused lol

 

nevermind, classic noob mistake, I forgot there was a SEARCH button lol

 

I got a P0420 in September or October last year. I just erased it with the scanner and it hasn't come back. But I'm starting to think that maybe something with the cat or an o2 sensor is bad, because i've noticed a drop in mileage.

 

It is the bank one pre cat oxygen sensor. I plan on replacing all 3 O2 sensors and the cat when I do mine. My mileage dropped from about 400 miles to a tank of fuel to around 250 miles per tank.

 

400?? That's really good for a 4x4... I filled mine the other day, the gas light came on and I drove awhile like that. It was at like 217 when I filled it... 217 miles on 1 tank of gas, I'm not too thrilled about it.

 

My mileage has dropped significantly since they started adding up to 10% ethanol to regular gas. I also had code P0420 a couple years ago. Put in dual-exhaust and a high flow cat and resolved that issue.

 

I was surprised about the mileage I was getting as well, especially with a 3.9 and the auto. It is 375 miles from my house to Kansas City, and I can make it there on one tank, and the low fuel light wont come on until doing a little city driving up there.

 

Yeah me too. Especially since mine is RWD. I don't know how much gas is by you but it jumped from 3.35 (cheapest I could find) to 3.55 now, it's crazy.

 

Gas prices as of today are 3.12 a gallon.

 

Well then you got it good. Lol, but it's ridiculous how much gas is... One day on ebay I saw a 2nd gen Dak that was powered completely on batteries. Its probably not powerful but hey you don't have to pay for gas either.