just a quick question. my check engine light has been coming on and going off. truck runs a little ruff sometimes when this happens and then clears up. light came on today and I ran it by my buddies shop. he scanned it and came up with p1133. air/fuel sensor. when I look the part up there are a couple of different ones. I know I need the upstream 1. also, I believe I have a cali emissioned car. it has 2 small cats before the muffler. I can see the sensor before the first cat and the second sensor after the second cat. just making sure I order the right part. would it be part #234-9003? going to order on line and pick up in store thru advance auto. that way I can save 30%. thanks, Jesse