ever since i got my exhaust installed (lt's, hi-flow cats, true dual 2.5") my check engine light has been on. I went to autozone today and they scanned it for me.

P1133
P1153

those are the codes that came up

the guy there said it was probably a bad o2 sensor or the wires go melted or something, i havent gotten to check yet since its already dark here.. is there anything i need to be concerned about or really look for?