Spoke too soon Hissing sound is still there (sssssssssssssssssssssssss) even after grounding. It seems to go away (like before) if ignition is turned off and back on immediately. Also when IBUS app is not running or is restarted, then no hissing sound. Do I have a faulty system? Or could it be that optional sound chip I have. Does anyone else have it?

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'05 E53 X5 4.4i, '97 E39 528, '07 E92 335i, '16 F86 X6M.