What does the 2011 chevy cruze code 4 mean?

Fault code P0004 (or, as You've said here, code 4) on the 2011 Chevrolet Cruze indicates that Your fuel volume regulator control circuit is high. This, in turn, indicates an electrical problem within the fuel volume regulator. There are a number of causes associated with this, so it's difficult to narrow down without more information. Is Your temperature gauge also running low or high Do You have coolant in the overflow tank Chevy claims that this is a very uncommon code to be getting, so You've broken something spectacularly ;). Seriously though, it could be something as simple as a defective temperature sensor. Don't worry too much, but I'd recommend takeng Your car in for a mechanic check as soon as possible.