is there away to tell what o2 sensor need to be changed without takeing them out all i no is the garage told me i need a new o2 sensor never told me which one

 

The code will tell you which one.

Judging from your screenname, I assume you have a 99 Jimmy. If that is the case, you will have two upstream sensors (the ones closest to the engine) and one downstream sensor (after the cat). B1S1 is the driver side upstream sensor. B2S1 is the passenger side upstream sensor. And your down stream sensor could be called B1S2 or B1S3 depending on the software revision.