2012 yukon error code P015D

[aztec]

Good evening everyone, today my CEL came on, so i took my truck to autozone and they told me it was :

P015D sensor delayed response
lean to reach bank 2 sensor 1.

i know it has something to do with the 02 sensors.

i would like to know where is this particular sensor located
front driver side (up or down stream)
rear driver side (up or down stream)
front passenger (up or down stream)
rear passenger (up or down stream)

should i check something else before changing the 02 sensor?
like a fuse or something else..

thanks in advance.
any help will be greatly appreciated.
2012 gmc yukon denali.