When the car is running I can hear the high pitched noise go on and off intermittently from only inside the cabin. When it is in accessory mode the noise stops and when I try to listen from under the hood there is also no noise. It does not get loader as I drive faster either.
My car has 160000 miles.
My car has an automatic transmission.
Good question. I believe you have a ground issue within your speakers or radio. In my experience, even if the radio isn't playing you may get a high pitch noise in the cab of your vehicle. If you have an auxiliary cable then you may replace it (this was my issue). There is an sometimes an issue where you have to put an adapter in the back of your radio to reduce the frequency inside the radio/speakers.
If you're unable to fix this yourself, consider YourMechanic, as one of our mobile technicians can come to your home or office to diagnose the noise you're hearing firsthand and help you fix it accordingly. I hope this helps and good luck.
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