So my mpg has dropped to about 10mpg all town driving in a stock 01 XJ AW4. My scangauge does not read sensor function so I am just going to replace the upstream O2 sensor. My question is does anyone have a recommendation as to a brand? Or can I just pick up any one from NAPA/AutoZone/.........all being equal. I have seen prices vary from about $40-$62. I was just looking for some input, any would be appreciated. (I usually just shop at NAPA)

 

Don't matter

 

NTK O2S's are the original equipment. Many XJ mechanics will recommend NTK Sensors.

The after CAT sensor does play a roll in gas mileage in that it's input to the PCM is compared to the before CAT sensor(s) where a goal air/fuel mixture is set by the PCM to adjust the fuel injectors dwell. A scanner that can display live O2S functions would be to your advantage so you can see if the O2S's are functioning properly.

 

I have no direct experience with this but I've read that Bosch O2 sensors and Jeeps don't play nicely together...