My 2007 Volvo S40 T5 AWD has an engine whistle at idle, but it stops momentarily when I turn the stearing wheel left or right, then comes back. Whats up?
Your best bet to get some ideas is to maybe pop the hood & see if you can give some clue about vicinity - even if vague. Also make sure it sounds like an actual whistle rather than say a soft squeal or something.
Whistling is about air and suggests a small vacuum leak. The connection to steering suggests an inspection of the serpentine belt (how old is it?) but that should be more like a squeal rather than a whistle.
High pitched noises can be hard to track down. If you get particularly ambitious a small length of hose works as a makeshift stethoscope - but watch the moving parts, especially the cooling fan which can kick on without warning.