Alright Cherokee forum, over the past year i have noticed that SOMETIMES (no noted reason) while driving my CL light will come on and when i check it via the key turning method i am flashed code 21 which is the O2 circuit. This code has also revealed itself here lately over the past week of when i drive home after school when the XJ has been in the heat for a while. The code never stays and it always goes away when i turn the XJ off. You can almost smell the jeep running rich sometimes and another symptom im having is that sometimes (again no obvious reason) my RPM will be around 1000 instead of the normal 800 or so. I just made those numbers up because thats what they look like on the cluster, anyway its just frequent enough to make me ask the question if the two events are related. So heres my 2 part question, does the code mean its time for a new O2 sensor because right now im assuming its stock (yes i know thats bad, the question is more focused toward the code aspect of the question). Part 2: Whats the best brand because i know jeeps have a problem with the bosch ones? (this is not going to turn into a debate about that ) Sorry for my short story here haha, thanks guys

 

Replace it. Go to rockauto.com and get an upstream NTK oxygen sensor

 

Alright I'll be getting that later in the week! Anything about the high idle?