What are common issues with the Audi A6's Quattro system?

I'm thinking of buying an Audi A6 with the Quattro all-wheel drive system. What are some potential problems I should be aware of?

The Audi A6's Quattro system is generally reliable, but some owners have reported issues with the Haldex differential, which is responsible for distributing power between the front and rear wheels. Make sure to have it inspected regularly to catch any potential problems early on.

One common issue with the Quattro system is the failure of the electronic control module, which can result in a loss of power to the rear wheels. It's important to have this module checked and replaced if necessary to ensure the system is functioning properly.