[Jo e Lefors]

First let me welcome you to the forum from Las Vegas Nevada.
Now for your question.
Yes it is a common and known problem.
It is most likely the subwoofer.
The subwoofer can be unplugged and the noise will stop. There are post with pictures if you do a search for subwoofer.
Briefly, sitting in the driver's seat with it slid all the way back. There is a plug on your right side at the front of the seat frame. Pull that plug and no more noise.
Please try doing the search first I posted some good pictures.

Good luck & take care.

JL

 

[Jo e Lefors]

Recently my 09 has started periodically producing a loud hum (like a blown speaker/amp) shortly after you start it. its slowly getting worse. It sounds like an amp problem but it can happen with or without the radio on. There is a box under the driver's seat and that is where it feels like its coming from.

Is this a know issues / common problem?

Checkout post number 18 with picture.
https://www.smartcarofamerica.com/f...ivers-seat-flood-car-update-54538/index2.html