I know there are two of them, an upstream and downstream. The upstream costs a lot more than the downstream one. My check engine light is on and I had it checked and the machine said the system was running lean. I put some sea-foam in it and that did nothing. I tried a higher octane fuel and it did nothing. So now, before I spend 135 bucks on new sensors, I want to see if I can possibly remove them and clean them up a bit and see if that changes anything. But first I need to know where they are located. It's a 4 cylinder XLT model. Any help would be appreciated.

 

welcome to FTE. you should update your profile so it looks like mine. post the code that you got..it is proabalby a P0171. The o2 sensor is fine it is just doing it's job, you probably have a vacuum leak, post more info for us.....any other symptoms? any work been done lately?

 

you probably should change the fuel filter and clean the MAF. either one of those could be your issue and they should be done as maintenance anyways.

plus I vaguely remember reading about a vacuum connection that breaks loose on these 2.3 duratec........i think it is on the drivers side down toward the bottom of the engine....

I looked on rockauto.com for O2's. Denso pre=$38 post =$31.........MC pre=$52, post=$38

some people(not me) change O2 sensors as maintenance at around 80k miles

 

Thanks powersmoked. I had it checked by the mechanic that lives next door. He grabbed the code and come to find out it is the MAF. I just replaced the air filter but Advanced Auto gave me the wrong one so guess I gotta get a new one. No more cheap stuff I'm getting Motorcraft. And I'm going somewhere else to get it this time. Thanks for your help though.