O2 Sensors and Gas Mileage

courtesy of Bob, The Auto Answer Man

I've been told that someone replaced their oxygen sensor on a Durango at about 80,000 miles, and they started getting about three miles to the gallon better gas mileage. Currently, I'm at 79,600 miles in my Durango, and it doesn't get the best gas mileage. I can go ahead and replace mine, hoping that my Durango will get better gas mileage. Or I can just leave it, pretend like nothing needs to be replaced, and don't worry about it until I actually have problems. How long do o2 sensors last, and could it be time to replace it out?

Well, it is true that replacing an oxygen sensor will result in better fuel economy if that is what is hurting your fuel economy. O2 sensors do get "lazy" over time. Not so much that they would be out of specification and give a check engine light, but enough so your fuel economy suffers. The problem with just "shotgunning" o2 sensors is that there is more than one, and they are a bit pricey. I am currently debating the issue with myself on my own personal truck. I have 110,000 miles and my fuel economy is down about three to four mpg. I had a problem with mine at 50k miles and changed them then. I am now +60k miles. My truck has four o2 sensors in it at around $80 each. You should change them in pairs (both fronts together and both backs together) in situations like this. Otherwise, half of the engine might be running different than the other half (due to one side running richer than the other side).
Good Luck!
Drive Safely!
Bob, The Auto Answer Man

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