just recently my ses light came on. so i went to autozone to get the computer scanned and got the code P0171. i know its bank 1 running lean. what i a wanting to know is what would make just the one side tun lean and not the other? i know it could be anywhere from a vacum leak to a o2 censor. i am thinking a o2 censor. but i just figured i would ask you guys.

last year i had the same problem but it was both sides running lean. come to find out it was the intake gasket leaking.

thanks

 

nobody?

 

in my old 97 5.4 i got one side running lean-front 02 sensor was bad. whats where id start.

 

i think thats the only thing it could be because its only one side. i would think if it was a vacum leak then both sides would be running lean. i could be wrong though.

 

I'm not thinking that way. That sensor is doing exactly what it's supposed to and the code is indicating such. Save your money in that case.

I'm thinking exhaust mani leak on the passenger side. You're getting unmetered air somewhere and unless that intake mani gasket is going bye-bye, that's a place to look.

 

i thought bank 1 was the drivers side?

i know that i have a exhaust leak on the drivers side some where after the manifold, but that has been there for the last 3 years.