I detected both of those codes using the ODB II system, what do they mean? is it a serious problem, what action may I take to fix this?

Vacuum leak maybe??? Visit gearchatter.com to look them up...and welcome aboard.

It means that both banks have gone so lean that the computer can not compensate for it. Have you had the air tract off lately? I would guess that the bellows isn't on the bottom of the throttle body right.