Randomly today, driving around. I was leaving Walmart when i started up my truck and the "check engine" light decided to show up. So i ran by Autozone and ran their free diagnostics and the left O2 sensor is what came up. My question is, can those just go out, or is there something causing this to come up. How would i know if it is a bad o2 sensor. To my knowledge it is the stock sensor. I have about 103,000 miles on her right now. Let me know what you guys think, and if you got any other information or comments feel free to include. Thanks

 

It could be something els causing the check engine light but I would start by changing those if they are indeed original there due anyhow IMO... If your gonna do it yourself make sure u have a torch as the heat of the exhaust basically welds them in there

 

Reset the code and if it comes back and points to the same sensor that is in all likelihood your problem. Visually inspect it to ensure that wires haven't come lose and rubbed up against exhaust and melted.

 

The code is PO171. They said it can be most likely a dirty or faulty MAF or a bad sensor. So i am going to clean the MAF tomorrow and clear the code and see if comes back

 

Doubt it's the MAF or both banks would be lean. You probably have a bad coil on whatever bank the lean code is on. Try resetting the code and swapping all coils from one side to the other. I the code shows up on the other side then one of those 4 coils is bad.