A mechanic just topped/added ATF into my 2003 Audi A4 2.0l, before that there was no fault in the gearbox. After topping up, I have an fault which says gearbox temperature out of range. What could be the issue? Is it an overfill? Or mixing of transmission fluids, since he didn’t know which one was in the gearbox but went on to add 3l of Dextron III G. What is the holding capacity of this Audi in terms of ATF?