what happens if you dont' have this replaced? (O2 sensor out)

 

The engine could start missfiring. It could also make the Cat Converter go bad.

 

With gas prices being what they are (and depending upon your driving), you could be out a couple of hundred bucks at the end of a year... Oh, and then there's the environmental impact...

 

You guys are such pesimists!

Nothing really that bad will happen if your O2 is out, mechanically speaking, now if something else goes wrong in the engine you wont have your o2 telling you some **** is going on.

It is worth getting it replaced, though I ran my last car for 50k without one and it was fine (i had an o2 simulator in)