Check Engine Light issue

[fullthrottle52]

Hello to all,

Just purchased a 2000 boxster. After 2 weeks the check engine light came on. Had private porsche mechanic check the problem. He put a reader on it and it came back with undefined porsche code and the numbers p1130 and p1128. He said he would have to take it to the shop to completely diagnose the problem. Any ideas as to what would cause these codes to come up? Boxter Light Codes say this would be a Oxygen Sensing problem. Any ideas what needs to be replaced.
He reset it and said it would probably return after so many starts. It came back today after 2 more weeks and maybe 20 to 30 starts.
Any help would be appreciated.

Thanks,