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Since yesterday, there is weird sound coming out from the front:















1.Only happens during driving















2.It comes from the outside















3.The frequency seems to be the same with the wheel















4.Not related to engine or transmission, because the noise did not change when I set transmission to "N" in driving, but no noise when parking(engine still on)































What could be possible problems? How long could it last until complete fail?































Thanks a lot!