It has been over 6 years and 85K miles since I replaced bot O2 sensors in my 2000 Acura TL. I'm not experiencing any negative sympstoms. Gas mileage is still steady. No Check engine Light. My question is: Is there any mileage or age consideration whereby it would be prudent to go ahead and replace the sensors. I've heard that after 80-100K miles the sensors tend to become "lazy".

 

Mines was 225k and no Cel just changed it to avoid changing it in the winter.
I've read about the slow response but the ecu will set a code when that happens.
I kept the old one just in case.

 

I'm still riding my stock +12yr old +200,000 Miles O2 Sensors... Still get steady 31MPG Hwy and 21-22MPG in the City.

I threat O2 sensors with the "If aint broke, don't fix it" method.. If you don't put Regular in your car and have a steady Preventive Maintenance schedule then they should be worry free.

 

I replaced my o2 after i got codes at 108k miles. I get 15 mpg city though!

 

Also depending on how much rust there is they may seize up giving you a hard time when in need of replacement.

 

If the car is running good and there's no CEL code, don't bother replacing the 02 sensors.....unless ya are bored. But, if ya do replace the sensor ..... make sure that ya don't put in a cheapo aftermarket part, you'll be sorry.