Twisted

Do o2 sensors degrade slowly over time, or are they more like light bulbs in that they either work or they don't? What are some symptoms of needing to change an o2 sensor? Thanks again.

93BlackNotch

They work or they dont, but some are more accurate then others...

Derf00

usually work or don't work.

Symptoms - there's only one real way to tell if an O2 sensor is bad, you will need a millivolt-ohm guage. Otherwise, you're just guessing. Guessing costs $$$.

http://www.babcox.com/editorial/ic/ic10044.htm
Look at the 'O2 sensor checks' section and 'Reading the O2 sensors Output'

PRO50SC

I've seen plenty of them lagging. They register but very slowly. That's not really classified as working or not working.

Derf00

take me literally...yes they do lag over time but they still work I guess that's not necessarily like a light bulb (on or off)

PRO50SC

Twisted

Thanks for the replies everyone, and thanks for the link Derf00. So there is some mixed info on the subject. I think I'm going to just replace mine, as it very well could be the original sensor that is in the car. Are they very expensive to replace?

Derf00

They're not too bad for your car $23 - $60 each depending on brand ($60 are the Motorcraft ones) Check them out here
Not sure how many you have on your car, 1, 2, 3????
https://www.rockauto.com/

89GTRed

theres 2 on mine 1 on each exhaust, I would assume that it would be the same on all the fox models.