My 2009 Accord has a metalic rattling sound coming from under the car in the back. This is not the annoying rear deck of the inside of the car, which is more of a plasticy sound that is much quiter than this metalic rattling. If I open the window this noise is loud. It is random - and occurs more frequently at high speeds when going over some bumpy spots on the highway.. Sometimes applying the brakes can start (or sometimes stop) the noise, but i think that is because that is similar to going over a bump. Anyway - does anyone know what is causing this annoying noise? I am about to take it to the dealer and i would prefer to go there knowing what it is instead of them racking up many $$$ at my expense. The car is under warranty, but they often find ways to get around that.
Thanks

 

First thing you should check (just to rule it out) is rattling heatshields around the exhaust pipes. They're mostly bolted to the floorpan, above the exhaust pipe. Hit em with your knuckes or with a small stick (nothing big like a hammer). See if you can duplicate the sound.

I'd put up a picture but I don't know if it's 2-door, 4-door, 4-cyl, V-6, or what?

Another possibility is a collection of small pebbles rattling around anywhere back there. Sometimes theres places for them to collect, like some flat surfaces on the rear subframe.

 

Thanks Jim,
I have a V6 4Door.
The rear brakes were so thin that it might have been them.
I changed them two days ago and haven't heard the sound again yet.
I will check it out though if it comes back
Regards,
Shaun