So I currently have 264000 on my TL, and have never had any of my oxygen sensors fail (or replaced). Should I continue to run with them until they fail, or is this a preventative maintenance type item that should be replaced? It appears as if many of the Ziners have gone through O2 sensors with way less miles, so I'd thought I would throw this question out there for feedback.

 

a fresh front O2 sensor is likely to give you improved mpg at your miles
the rear one just makes sure the front is working

 

I have 222K miles on my original O2 sensors. I still average 25.5 mpg so haven't bothered preemptively changing them. My 2 cents.

 

I agree that a fresh front o2 sensor can help mileage, but you can't ignore the rear one either. Under some conditions, the ecm will ignore the front o2 and use input from the rear only.[typically if it thinks the convertor is at risk] I saw a study that car quest tech training published where rear o2 values were substituted about .2v-.3v high and low. Fuel trims changed about 40% + and - accordingly, and fuel consumption changed from 20mpg with a working sensor to 25mpg with higher o2 voltage, and 15mpg with lower. The cel never came on although it did store pending codes, possibly for both rich and lean if memory serves me. Still, most manufacturers claim the rear has from 0 to 5% of the input for fuel calculations.

 

you can possibly see an improvement in gas mileage if you replace all o2 sensors with new ones. If your mileage is good though, I wouldn't bother replacing until it fails.

 

how do you know your mileage is what it can be,,
unless you do some simple maitenance?

its not like o2 sensors are that expensive,,compared to other parts of our car!

back in the day: it was suggested replacement at 100kmiles!

 

Thanks for all feedback. I have decided to replace for good measures. Is this a dealer only part, or can I purchase at an auto parts store like Advance or Autozone?

 

Try rockauto.com, they have the Denso brand which is the exact OEM at about half the dealer cost.

 

How tough are these to replace? Any pics showing location and any problems with install?