code help

[Hopeful]

I posted this here as well because 18 people have read it but 0 have commented...

So I pick up my new-to-me 08 cc (79,142 on the clock) tonight from the dealership. I'm driving home and after 50 miles(first half stop and go traffic jam, second half steady 50-60mph) the SES light comes on. I get home and check and its p0138 (o2 sensor). I have two questions:
*1 is this something that just happens or is it likely the dealership cleared it so as not to deal with it?
*2 can i fix it myself? (will some cajun b-pipes solve the issue?)

Thanks!

[04titanss]

O2 in the B-Pipe on the drivers side has bit the dust, time to change it, not a very hard job to do.

http://nissanhelp.com/diy/obd_codes/p0138_nissan.html