I have 92K miles on my 01 Santa Fe 2.7 AWD. Should I be replacing the oxygen sensors? They have never been replaced. I'm getting about 20-22 mpg. If I replace them, should I just do the ones before the converter?

 

It depends. Do you have any REAL reason to change them? Did you fail emissions?

Is 22 mpg bad for you? Why do you assume the O2 sensors are bad?

 

No real reason. I just changed the O2 sensor on my S/O's Jeep. It had a warning light on, but seemed to be running ok. After changing the sensor, it runs really, really smoothly - much smoother than I ever remember it. It had 75K miles on it. I was just wondering whether these deteriorate with time and a change would improve all round performance and efficiency.

 

It wouldn't hurt to change them, but I'd be looking at other things first.

Did you change the timing belt? Fuel filter? Spark plugs? Air filter?

 

Timing belt was changed at 70K miles
Spark plugs, wires and air filter at 75K
Fuel filter has not been changed. Is that a big job?

 

Depends on if it's in the tank or outside. Official website is not reliable on that point, so I can't tell you.

 

As for the oxygen sensors, I haven't seen anywhere it suggesting changing them at a certain intervals on my 2005 2.7 V6 (63,000+miles), not even the Haynes manual. It suggested changing them in my Toyota Tundra around 80,000 miles. I waited until the check engine light came on around 90,000 miles to do it, and did all four myself and didn't notice one bit of difference in MPG or the way the vehicle drove (the Tundra that is).

As for your MPG, it seems to be right where it should be. The biggest things I do for my MPG is oil changes, tune-ups and I recently cleaned my throttle body and MAF sensor which did seem to make a difference in my RPMs.

The fuel filter on mine is in the tank. I thought about changing it and when I talked to the people at the dealership they told me they haven't had to change one yet, so I decided against it. I use decent grade fuel and fuel system cleaner every oil change so hopefully that will help. I pray that if/when it does go it gives a warning by driving sluggishly and not a complete failure. I guess that's what AAA is for.