Friday I had my car scanned and no codes showed up. So my question is even though no codes showed could it be that my o2's still need changed? I'm getting around 230 miles to a tank with my driving and about 255 if I take it easy. What are some other things that would help my mpg. Plugs and plug wires are about 4 months old.

 

hmm im getting like 230 and i thought that was normal lol... my o2s may be going south, and my opti already did... with only 47k miles

 

If those are original O2's, they are due for a changing.