I have an 08 HHR with the Premium 7 speaker system. Just recently noticed a rumbling sound almost like distant thunder that comes from the subwoofer intermittently.

This can happen with the radio off and/or on. It happens when the car is running and off. It happens when you first stick the key in the ignition but have not turned the key.

The past two days my wife drove it to work and back heard nothing until she got turned the car off and pulled the key out.

Any ideas before I go to the dealer?

Jim C

 

ground or power wire is shorting out on the amp. prob got pinched some where. let the dealer look at it.

 

There was a bulletin about speaker noise that required a reflash of the computer, but I think that was just '06 models.

 

That was a loud pop noise when turning car on or off.