Vichtz

Id check ground first, ghost theory aside. Also check any EMF interferance from the alternator, although since its a factory option it is doubtful that could happen, but happened to my freind when we installed his aftermarket radio. Also, a speaker wire could have come loose from its harness and is hangin too close to a power wire. But more likely than not its merely a loose ground, though I would get it checked cause if that was the case you would ONLY here the noise when radio was on, not with AUX. Have you checked foreign objects too? like magnets or a phone or something? GPS nearby? Anything spitting interference?

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