my max has 100k miles on it right now and most of my driving is highway....i get about 18mpg and i have replaced my knock sensor....air/fuel filters.....new spark plugs recently.....

i dont have a check engine light but i think if i replaced my o2 sensors i would be gettin alot better gas mileage....i baby my car so i dont get why my gas mileage is so bad.....

if i were to repalce the o2's which ones do u recommend me changing out?

front or back?

 

good question, I also would like to know if one is more prone to dying...