I had a 2006 with the same problem. It was an intermittent buzzing sound. I had it to the shop probably 25 to 30 times before they found the source of the problem. It was the radio. After replacing the radio the bizzing went away, but they ended up replacing the new radio again because the CD player didn't work. I also had the same thing with the tire pressure monitors. After having them fixed somewhere around 50 times, they never did get them working right. Those were only two of thousands of problems I had with that car. Finally, after complaining to GM and the dealership where I bought it, GM repurchased that car I called the Chevrolet Impala and sold me a truck. I hated that Impala because it was nothing but trouble. If I were you, I would get out of it as soon as you can.

I noticed a buzzing sound coming from my turn signal instead of the normal tick. I had just bought my brand new Impala and took it in to be fixed. They tried several remedies of which none corrected the problem. The car has been in to be fixed 5 times since and in the mean time developed a new problem. The tire pressure gauge system was reading incorrectly. This was attempted to be fixed on the 4th and 5th trials. The car was just taken in again today for the 6th time to try and fix the very same problems. The service manager said that the tire gauge system has been misreading in all the Impalas, but he's not sure about the buzzing turn signal. I told him if this doesn't get fixed correctly this time and a remedy isn't found I will be asking for a replacement car. I can't believe I spent over $30 thousand dollars on a car that I've had in the shop 6 times already. I love everything about the car except for these problems and I really want to keep it. The service dept. is great, but I just don't think they know how to service my car.