hi i have 2002 Audi A4 Avant 2.5 tdi quattro tiptronic box I am having problems with the auto box. After driving for about 15/20 mins I stop for about 15 mns start up and drive off and the box won't change up. Sometimes the p.n.r.d.s letters light up like a stencil when this happens .Also I put it in sports mode when it starts to malfuction ,then it starts to change up .Then I put it into normal drive and its ok till I get home after about 15 mns. I have tried disconnecting the battery over night with the hope it might be a computer fault. Is it low oil in the box or an electrical fault.