So I just had a CEL pop up, and it read as P0172. A quick search says this could be a MAF or a o2 sensor. If it was the MAF I would think both banks would be reading rich (or lean) and i'd throw both p0172 and p0175. This leads me to believe its an o2 sensor and not a maf. Correct me if i'm wrong.

If i'm on the right track, i'm thinking its the pre-cat sensor, as the post-cat sensor has nothing to do with fuel trim.

that said, where's the cheapest place I can buy an o2 sensor? Also, which side is this on? Passenger side or driver side?

thanks in advance 6speed!

 

I picked up my 02 sensor from here.

http://www.autohausaz.com