I've seen reference to the muffler rattles, but can't find an exact match.

When I close any of the doors on my 2011 G37x sedan, I hear a "thump" under the rear. It sounds like it's behind the rear quarter or muffler area. It's a single "thump" or "thud" and I hear it on both sides of the vehicle. It's a metal on metal sound.

I've heard a faint "rattle" from that area over the summer, but didn't pay close attention. Today the weather turned cold and it's a distinct single "thump" after closing the door. I don't hear it while driving or inside the vehicle.

I'm planning to crawl under there tonight, but am open to any suggestions on where to look. Trying to avoid the stealership as they fix one thing and break 2 others in the process.

Maybe it is the "muffler rattle" that I see everywhere in the search results? Is it still a problem on the 2011+ and if so, is there a TSB?

 

mines does that too. 07' sedan model though. My hypothesis is the vents inside the trunk. each vent has a flap that airs the car out. When you close the door, you're forcing the air out through the vents causing that noise. It's gonna be located under the trunk's carpet. Put your hand down there and you'll feel them. I think you can even see them.

 

You may have identified it. It sounds like it's something solid hitting sheet metal behind the rear lower quarter bumper. It's not hitting the plastic bumper but rather sounds like sheet metal behind the bumper. I greatly appreciate your feedback, as I wouldn't have thought of a vent like that to explore.

I'm interested to know if anyone else hears this, if it's "normal", or if there are any creative solutions. Now that I know it's there it's p*ssing me off!

 

is your license plate/frame/bracket rattling?

 

Nope. First place I checked after having a mid-80's monte carlo with fill up behind the license plate.

Thank you for feedback.

 

It was indeed the "flaps" covering the vents (somewhat) accessible from the trunk. Never would have thought of looking there...

 

I asked the dealer this question and they first said they hadn't ever heard it, but dug into it and the noise is by design - venting for the cabin when you shut the doors. It's a good idea since the cabin is so tight and having too much air pressure pushing out while closing doors may cause issues.

 

Not that I have the same noise but I am curious and will go look for those vents today. Nice suggestion

 

Now I know where all my farts go

 

I think we should seal your vents.