lucasb7

Hey guys, I think this might be my first thread here but I've been lurking for a while

I have a 2012 A6 3.0T (basically exactly snagitseven's car but one year older) with ~55,000 miles on it.

Lately, I've been more aware of a rattle/ratcheting sound from the engine around 1400rpm, particularly noticeable when the engine is slowing. While it is most noticeable when slowing down while driving next to cars, it happens in every gear (incl. neutral).

Have any of you experienced a noise like this? It doesn't sound terribly catastrophic but as I approach the end of my extended warranty I want to know if I am unique in having this noise. If not, I'd like to get it checked out.

A video of the sound is uploaded here:
Thank you in advance for your feedback and all of the other contributions on this forum I have benefited from.

porksoda

sounds like a pulley bearings gone bad... try to see where it comes from when parked and open the hood and listen for it.

Silver42

What about the Chain Tensioners? I am not sure about that though as I would think that it would make noise at all RPM's

blackc7a6

I had the same sound on my 2012 too...it's the cats rattling! I ended up having a secondary air injection port cleaning done at the dealer under warranty (which has been extended to 120K) and during the service they cleaned the valve seats by hand. They said the carbon build-up caused the engine vibration making the exhaust rattle. the vibration was drastically reduced after the service and any residual sound got covered up by the awetuning touring exhaust with downpipes. If you have a Vag-com check for Secondary air injection flow soft codes or have the dealer take a look if you're under warranty. hope that helps!

lucasb7

I think this is it! I did some googling and found this that perfectly matches my description (I think one of the replies may have even been yours). The poster had an exhaust crack so I'll have the dealer look into that. I have vag-com and there are no engine related codes pending or not.

Along the same lines, I do have a loud whining noise at startup/cat light off that sounds like a secondary air injection pump biting the dust. I'll have the dealer look into that too.

I suspect there is some carbon build up as well but my understanding is they will only address this issue if there is a MIL?

porksoda

I had flex pipe noise which was like metal noise but wasnt a rattle replaced under warranty and over a year later the flex pipe noise is back again.

your rattle seems intense, perhaps try what others have suggested re cats.

kevrhof

Those video skills tho..

Vodka G

I had the same sounds on my 2012 as well, dealer replaced cat and reso under warranty, not sure about the sec air injector port but its def the cat and the resonator

NABS4

Also, I think the cat has a longer warranty since it's under emissions which is longer than the standard warranty.

JaxxOne

The problem is very common, its the flex pipes on hour exhaust. I had the same problem, replaced them and the sound went away! You cats are fine