Ok so I now have a check engine light and i checked the codes and one is the P0138 and the other one i can't remember but its the other oxygen sensor code which i looked up is the oxygen sensors, now i heard those go out a lot. my question is when the durango gets above 75 like 80 or 85 the engine light will go off for at least a week then when doing the speed limit for a week or more it comes back on is that normal and how do i know for sure that the oxygen sensors need replaced?

 

P0138 1/2 O2S Shorted To Voltage

Could just be corrosion, or it could be there are some deposits on it. Just go on www.rockauto.com and buy the OEM style and in the brand NTK or Desno. It will be a lot cheaper.

 

I had that. In my opinion, when the O2's start throwing codes, swap out the O2's and the cat. When a sensor triggers, I never first assume its a bad sensor. It's an old vehicle and you are having issues with a part (the exhaust/cat) that you know is a meant to be occasionally replaced. I'd say now is the time.