I've done a search on this and was wondering if I could get a "definitive" opinion:

Will driving with a bad downstream (post-cat) O2 sensor....

A. Cause any damage.

or

B. Put the car in "limp/safe/etc." mode, causing poor fuel mileage/performance, etc.

Thanks in advance for your help.

 

Nope. I ran w/o one for years and years.

 

Good to hear. I guess all I really have to be concerned about then is burning out the CEL!

Thanks for the response.