I was driving my car down the high way and then all of the sudden i started hearing a high pitch sound coming from my engine bay. I'm thinking it may be a boost leak but i'm not positive. My mkv just hit 70,000 and i don't have an owner's manual so i'm not sure if i missed any "check ups" for my car lol. it appears to be coming from under the engine on the left side. it is extremely high pitch as if it is an alarm going off. when i turn my car off it keeps going and then slowly quiets down. it also silences every time i begin to accelerate. at first i thought my serpentine belt needed replacing but i don't think that is the case.