Just wanted to share my experience with the group... I have a 2011 xS coupe nearing 80k and I ran into the terrible cat rattle just a couple of weeks ago.

I called the local dealership and they told me I needed a CEL to replace the cat under warranty, otherwise it was a $1300 repair bill. Decided to call another dealership and they told me that just the rattle noise had to be present and confirmed internal to the canister to be replaced under the 80k emissions warranty.

When i had their tech look at my car they denied the claim saying that the CEL had to be present. I had them call consumer affairs and they confirmed that a CEL typically needs to be present, HOWEVER when the honeycomb material breaks apart internally, they make an exception and corporate takes the defective converter back and runs an emissions test on one of their test stands, in which case the catalyst tpyically fails to meet emissions standards and 9 times out of 10 corporate will reimburse the dealership for the repair bill.

So I'm at 79,8xx miles and getting a $1,300 repair convered under the emissions warranty. If anybody else is dealing with this rattle and the dealership wont warranty the cat because a CEL isnt present, CALL CONSUMER AFFAIRS!

 

Had same diagnoses. Honeycomb fell apart. Lot of rattle. Dealership offered to fix before I even said anything about it - no CEL present.

 

sorry to hijack the thread, when is the rattle heard? any rpms? or mostly around 1,500?

 

In my case, it was at idle and at low RPMs. Once I got over 3k or so it would go away completely or be very faint.

 

I'm getting a little rattle just as i accelerate from a stop. not sure if it's a loose heat shield or this. none of the heat shields are obviously loose, but how can I tell the difference? I have about 15k for it to get worse before the emissions warranty is up.

Just saying, if my dealership told me $1300 for new cats, i'd be putting aftermarket pipes and HFC's on. Replacing failed stock parts is my favorite way to mod on a budget.

 

From what I can tell you can't really tell a difference. Luckily, my mechanic looked at it for free (family throws a lot of work his way) and told me that's what he believed it to be. I got lucky again because when I brought my car in for maintenance they offered to replace them before I even said anything.

Still would be looking to swap for after market though

 

Can you guys post a video of the rattle by chance. Im thinking I may have this issue

 

mine is currently too intermittent to get on tape without driving around recording for an hour. If i had to describe mine, it almost sounds like engine knock, but clearly originating under the car rather than from the engine.

 

I have this weird intermittent rattle like sound around 3-5k rpm. Trying to figure out if the cats are my issue

 

This. My cats made my stomach drop the first time I heard it because I thought it was a rod slapping around or a bearing had spun loose. It's not as fast paced as a rod knock and it doesn't get worse as the RPMs climb which led the the cat discovery.

 

That's exactly why i suspected the heat shield or cat. It doesn't have any characteristics of engine knock other than the sound.

as soon as i can reliably get it to rattle i'll bring it in to the dealer

 

does it sound more like a loose bolt or nut rattling inside the cat? i think that's what i hear when i have my window rolled down and the sound echos off the wall when i'm driving near one.

 

I started getting the cat rattle 2-3 months ago in my driver's side cat. Mine can distinctly be heard from the inside of the car sitting in my garage between 950-1150 rpm. Holding the throttle to 1k pretty much sets it off. From what I'm guessing I probably have a few months before the completely collapse.

I was quoted $860 from my mechanic and +$1k from the dealership to get it fixed. I'm thinking of getting RHFC, but I live in CA and don't think they'll visually pass smog. I might get them and just weld the cat cover to the bottom of them to make them look stock.

For those asking, it sounds like lose nut bouncing around. Previously it was louder inside the car, but now you can definitely hear it outside. Here's a video of it happening for a few seconds. Note: you'll have to turn up your volume probably to max to hear it.

 

Yesterday, I had my passenger side cat replaced under the factory emissions warranty (2013 sport sedan with 35K miles) for the same issue. It was intermittent at first, but over a period of a few months, it started to rattle (like a penny in a tin can) more consistently so I took it in and they confirmed. I'm hoping that the driver's side cat goes out before the warranty is up as this is close to a 1K$ repair. I also had to have the TCM reprogrammed because of an error thrown (I believe there is a cryptic oil cooler TSB for this), but I had to pay for that since my car is 2 months beyond the 4 year bumper to bumper warranty. The transmission seems more behaved now during lower speed shifting.

 

I have a 2013 and had that update as well. I am getting better MPG but DS mode is much less aggressive when rev-matching. Also, my Cat was rattling but replaced with no CEL.