Fault codes : P1577/P1573
 

Those are your main motor mounts. I would do a visual inspection before deciding what to do. Obviously look for basic issues like unplugged connectors. More seriously, see if either mount is blown--split apart and/or oozing the hydraulic type oil that is inside them. If they are physically compromised and it isn't just wiring, I would replace. Blown ones put unnecessary stress on any remaining mounts (including torque mount and back at tranny), general drivetrain roughness/vibration, etc. If you find physically they are okay, then up to you--the function electrically is to make the motor yet smoother in feel but if not blown then basic drivetrain support has not been compromised.

Could you point me to picture or video of it how to locate them please, I will check?

See Items 4 and 5 in the first post in the Sticky at the top of the D3 Thread.

If you forgo this and manage to find a youtube video that shows you this information, including the proper way to remove and replace the mounts along with torque specs and which fasteners to replace and which ones are Torque to limit which have specific procedures to follow so your powertrain does not fall out under load from snapped bolts etc. Print out this for your garage:

https://cimg5.ibsrv.net/gimg/www.aud...342a952ddf.jpg

It is a four year old thread that we locked to prevent posts from cluttering up the thread. Just google the link and an updated link will come up:

Audi Teilekatalog Parts Catalog Online

You should consider getting a repair manual. Or, find a research librarian...or maybe Google...to work for free?

Modestly priced basic online manual w/ subscription access: http://alldatadiy.com

Agreed. And Alldata always has a coupon going, just do a google search to find one.

I finally was able to get under the car and was able to spot the engine mounts .
They are psychically good.
I also tested by giving acceleration and checked engine, and it seems stable.
But when I went under it oily all over and the electrical wire and connections are oily, I am guessing this oil made the sensors to go bad.
I had to top off oil few times and it appears this is leak is the cause of the low oil level.
I was watching few youtube videos and they are talking about valve cover gasket and may be some o-rings inside which is common problem for these vehicles.
If I open the engine for gasket replacement may be possible o-ring, could tell me know precautions to take please?
https://cimg3.ibsrv.net/gimg/www.aud...44565001df.jpg

#1 precaution: Observe all proper tightening torques for all fasteners you need to remove to access the sensor(s), valve cover gasket etc.

Do not attempt any repairs on the engine without the service manual.

I have no idea what "O-Rings inside" are being discussed in the youtube video. Then again, I am no Youtube Certified Master Auto Technician.....
https://cimg5.ibsrv.net/gimg/www.aud...06969b757d.jpg