My check engine light is on. I can hear an air leak towards the back of the engine. It's high pitched so I am assuming it's small. When I push on the gas everything is fine; it's when I let off the gas pedal the whistle is noticed. Is this an intake air line, is it the turbo line, or something I don't know about? Any input helps, thanks. Also I'm a fan of Haynes manuals but they haven't made one for this year model yet does any one have any other good manuals for this year/model?

 

look carefully, hard to say...
a high chance of a broken check valve