A short casting can cause a sudden loss of brakes, increasing the risk of crash. The electronic parking brake and its emergency brake function are not affected and will still function.
Service Brakes, Hydraulic — Foundation Components — Master Cylinder
Audi has notified owners, and dealers will inspect the brake master cylinder, replacing it as necessary, free of charge. The recall began May 3, 2019. Owners may contact Audi customer service at 1-800-253-2834. Audi's number for this recall is 47O9.