P0138 annoying code
 

Ok, I had the P0138 code, comes and goes. I reset it. It came back, P0138 is for the o2 sensor. I replaced my upstream sensor. Came home a bit ago, CEL on again, P0138. WTF? Is it an error code, just popping up for ha ha's? OR do I need a downstream sensor? I looked it up and it also says possible 12v power short. P0138 is o2 sensor over volts? Any info would be great.

That code is for the O2 after the cat.

Did you check the fuse in the junction panel?

Yah, this happened to me, it would throw the code randomly, over a few months. I just replaced the downstream o2 yesterday and it hasn't thrown it just yet...but yeah, check your fuses first.