Ever since my 3.4 swap, which was like 3 or 4 years ago, I keep getting the 'rich' code. I never thought much of it but it keeps coming on more often and Im not getting too good of gas mileage. Could this possibly be from a bad O2 sensor?

 

first culprit yes. 02 usually needs replaced about once a year, I mean they are only like 20$

 

Thanks for the quick response.

Haha, well, I dont think mine was ever replaced.....How do I test it to see if it's good or not?