how do you know if the O2 sensor is bad?

[Vendor Defendor]

just wondering how can you tell if an O2 sensor is bad? i am wondering if mine is on the way out... but its only a year old oh well

 

[d0n_3d]

if you start seeing o2 mvs that are very settle...like they only stay in one range...or you start getting 0 cross counts...a bad o2 causes bad fuel mileage, also when it's officially toast, the service engine soon light comes on and throws a code 13 i believe...

 

[gn79]

What kind of o2 is it and has it seen any high octane. If it is a bosch it is most likely bad by now. Try to get a denso o2, they are about $25 dollers and they hold up read good. I was using the bosch o2 for a while, I got a denso and Its been about close to a year now and it is still working like the day I got it.

 

[jdodman]

I use Denso (Sparkplug.com) and they are great. Much more lead tolerant than anything else, and when they start to go, they throw a soft error code (Service Engine light comes on for 10 seconds, then clears.)
That is what I use, and how I know when it needs attention.
Purchase two (25.00 each) and throw a new one and the correct open end wrench in the trunk, just in case they start to go at a bad time. Like the race track...

 

[Vendor Defendor]

i have the AC Delco O2

now, what i have noticed, this maybe a tail tell sign, not sure though, is it seems like, once i get up to speed, and the car shifts gears, lets say onto 3rd, and i let off the gas the o2's bouce around in the 800's until i get back on the gas then the start going all over again.