So I noticed this last night as my wife and I were driving home. The sound seems to come from under the hood but I can't really pinpoint the location.

It sounds like a piece of plastic is being knocked up against a sheet metal part of some sort by a spinning part. There is no real rhythm or cadence to the rattling sound but it doesn't get louder or more pronounced if I rev the engine. It just seems to occur when I am slowing down and then it fades in and out (again with no real pattern) when I'm stopped at a light and it's loud enough to be obvious. This is on a 2010 Sport SC and I didn't find anything in the search field that matched my symptoms.

I know it's not the fan clutch because that was replaced twice so I now what it sounds like. I'm pretty sure it's not engine knock because it has no steady cadence and it's not consistent. so I'm a little baffled by what it could be. I ran a scan and this is all that came up... No real red flags here as far as I can see. Does anyone have an idea as to what may be causing this?

ABS-Brake Module

U0126-00 (A Lost communication with steering angle sensor module
( on 31-08-2016 22:26:05 at 91320 km )

BCM-Body Control

C1A57-14 (6C) Front left initiator - General electrical failure - circuit short to ground or open
( on 13-08-2016 16:14:07 at 90778 km )

HCMB-Headlamp

U0415-00 (2 Invalid data received from ABS control module
( on 17-08-2016 18:04:14 at 90807 km )

HVAC-Ventilation

U0422-86 (2F) Invalid data received from the body control module - Bus signal/message failure - signal is invalid
( on 13-08-2016 12:53:54 at 90778 km )
U3000-55 (2F) Control module - System programming failure - is not configured
( on 13-08-2016 12:53:54 at 90778 km )

IPC-Instrument Pack

B1A85-96 (2 Ambient light sensor circuit - Component failure - internal failure
( on 13-08-2016 21:41:23 at 90789 km )

PDM-Passenger Door

B110B-11 (6C) Rear door passenger side central locking motor - General electrical failure - circuit short to ground
( on 18-08-2016 21:15:25 at 90883 km )

I also shot a video and was able to recreate the problem on deceleration. Here it is

Hi, sounds like maybe catalytic converter insides rattling or exhaust related, I'm sure other members will be along with more qualified ideas soon, but yes sounds exhaust related to me.

Thanks for your input Gilly. I really hope it's exhaust related. Much cheaper than an engine related issue.