Originally Posted by ssewannabe
What'* the mileage on your car? I've heard that oxygen sensors should be changed after 50,000 miles. They might have an effect on your mileage, I don't know first hand.
I've heard that they should be changed every 60,000 miles; some people also say "if it ain't broke, don't fix it."
Regardless, mine are least 90,000 miles old and I still get decent mileage. Replacing both will put a small but noticeable dent in your wallet.