apoorvh1

Hi Folks,

I have an Audi A4 2003 Quattro. Yesterday, I noticed a weird sound coming from rear side under the car. It is coming both while driving and parked.
It looks like coming from around a white housing near the catalytic converter. I can see some oil leaking there.
I have attached pictures and video.
Anyone please tell me why the sound is coming and what that leak is?

Rsniper4

From the sound, it sounds like a pump of some sort.
As for the leak, its most likely the result of a leak in the rear differential housing. If that leak has been there for a long time, it would be a good idea to get that gear oil inspected and refilled if necessary.

apoorvh1

Thanks Rsniper4! I had forgotten to mark this question "Closed" as 1 week after posting, I had found the issue myself.
I lifted the car up and found the noise to be coming from the fuel pump. Changing it was a breeze.
I was not sure since when that gear oil had been leaking so had it changed.

After these changes, the car throttle responsiveness has never been better.