Hoping someone may have a suggestion here is the history and the problem.

• In spring the ESP light tripped on my audi a3 3.2L 2007 quattro
• I ran VCDS scanner and it showed pump / controller related issue
• I changed the haldex oil and filter
• This did not fix the problem
• Due to money I stopped and we drove the car with the light on
• Given it's now winter I bought the pump on a chance and put that in
  • Did not change the oil since was just changed in spring and less than 2500km put on it
  • Cleared the codes and ran the tests against the controller and pump (No errors found)
• Drove the car for about 1 week then we noticed a intermittent vibration / howl from the rear end when going up a hill or maybe when hot ( not sure the trigger for the noice / vibration )
  • There are no codes registered
  • When you step on the car the car is defintely in awd and verified this with the VCDS utilities

Does anyone have a suggestion as to what would be the reason for the vibration ?
- Car has +200K on it
- Tires are all good and tire pressure the same
- Would changing the oil and filter again might cure be advised ?

Thank you in forward
Sheldon