Search but did not find anything on the SC430 forum - my bad if it's already mentioned before. When all windows are rolled up and the engine is running, I can hear a constant (small) hum coming from the back (I think it's coming from the trunk). I put my ear against the rear speakers and hear nothing - Could be coming from the sub. Was wondering if any of you have this issue and how to solve it? Thnx

 

It's probably the fuel pump, nothing to worry about. To verify, lift up the rear seat cushion, and the sound should get substantially louder.

 

Thnx for the quick response. Wasn't really worried but was kinda puzzled Anyway, thnx again.

 

The other possibility is the ML amp...passenger side, under the trunk floor and behind the rear seat. The fuel pump is directly behind the driver's seat, so that should help you isolate the noise.

 

Like Bob said, it very well could be the ML amp's fan turning on because it is hot. This has been covered in earlier threads within the last year or two, I think, at least it was recent enough for me to remember...