When should I know when I should replace my o2 sensor? I bought my car 2 years ago so it hasn't been changed for at least 2 years and also i run about 280 per tank of gas in my 98 gsr. Is there any signs that will tell me when the right time is?

 

with an oscilliscope and a little know-how you can test your o2 sensor.

other than that i dont think there is a way, they live around 100k miles.


telling how many miles on a tank you get is a really bad way of telling your mileage: some fill up at 1/4, some fill up when the light turns on, some fill up when theyre down to the last ounce. and even then not everyones gauge is calibrated the same. fill up, (dont top off) and next time you fill up (again dont top off) and divide miles by gallons and you have your mileage, take that over a few fillups to average out any innacuracies and youve got yourself a statistic.


anyways, anything below 25 with mixed city/highway and i would replace it just cause you dont know the last time it was done.

(edit)

also, if your not good at math like me, you can get a calculator at walmart for a dollar to keep in your box, its how i track my mileage.