2004 Audi a6 Facelift

Hello I sell my beautiful well-groomed Audi a6 the car still has 14 months tüv, car has got 4 new all-weather tires,new windshield.brakes were completely renewed last year,right side new drive shaft was renewed . The only problem the car has defending the ride is the transmission goes from d to s over car but continues normally. Unfortunately, I do not know why. Since I don't need a big car anymore, don't invest .auto is stainless because the İst galvanizes.If interested please report