Need OBD-II Code Explaination
 

My "Check Engine" light came on yesterday mysteriously. I friend of mine used his Scantool and grabbed this code: P0174

In my Haynes manual it states this description, "System adaptive fuel too lean (Bank2)".

Can anybody please enlighten me a better explaination. Do I have a bad injector? fuel pump? what cylinder went lean? etc.

Any help would be much appreciated. I own a '97 Cobra.