Hello, I just bought a 2000 Dodge dakota crew cab 2wd 4.7 auto. 135k miles.
It runs off gas and CNG. My problem is. I was driving home from the USED CAR LOT and my check engine light comes on. Code is p0138. Which is my downstream o2 sensor is putting out to much voltage. I popped the hood and noticed I don't have ANY o2 sensor relays. I have two spots for them in my engine fuse box. Am I missing the relays or did my sensor go bad?
Thanks for your help.

 

bump????

 

ummm....I am pretty sure that your supposed to have relays in there for your O2 sensor's.

 

ThaNKs for the reply. I am going to change out the o2 sensor and then see what happens. if its still the same problem i will buy 2 new o2 sensor relays and post the results on this thread

 

before you spend the money on the relays, buy a repair manual and read through it to make sure there supposed to be there. It is a good investment to have.