Sheldon :I

Sheldon: Oh, good. I’m not keeping you from anything. Your check engine light is on.

Penny: Mm-hmm.

Sheldon: Typically that’s an indicator. To, you know, check your engine.

Penny: It’s fine, it’s been on for, like, a month.

Sheldon: Well, actually, that would be all the more reason to, you know, check your engine.

Penny: Sheldon, its fine.

Sheldon: If it were fine, the light wouldn't be on. That’s why the manufacturer installed that light, to let you know it’s not fine.

Penny: Uh, maybe the light’s broken.

Sheldon: Is there a “check the check engine light light”?  O-o-o-oh!