I know this has been somewhat discussed already, but it seems to go no where. I'm having this issue and have had it off and on for the last 2-3 years. After multiple relay changes, a Hydraulic pump replacement 6 months ago (problem has returned after 6 months on a warm spring day), now BMW corporate and dealer wants me to replace the SMG control unit (about another $1400). BMW corporate is refusing to admit there could be a problem inside the pump itself. They're now telling me if the control unit doesn't fix the problem, they want to replace my entire transmission? Problem is, I live in a very hot climate, inland in Southern California where 80degrees is on the cool side. Anyone else out there had this issue and have a successful "replacement" story? BMW NA says they know nothing about this issue and are not being of any help at all. They are refusing to honor the warranty on the pump, because they say now it's not the pump. Bottom line is, they were either wrong on their diagnosis of the pump in September, or are wrong about the diagnosis now (of the control unit).