Just bought an 08 Lucerne Saturday. Failed emissions today due to the system showing not ready. They said it needs to complete its drive cycle. I just bought this car and the guy I bought it from didn't say anything about this at all. The car drove perfect the first two days I had it. Then this evening after work it gives me a message on the dash saying "tighten gas cap". After refueling I cranked it up and that message went away but now my AC, heat and defrost won't come on. I don't know what's going on but I've got to get whatever it is fixed ASAP so I can get this car registered in my name. Anyone have any insight on this ? Any and all help would be greatly appreciated!