Yeah, I know it’s a bike forum but hopefully somebody might have some ideas.
My car, a 2003 BMW 3 series, has recently taken to cutting out while I’m driving It’s done it 3 times in the last week. Each time it happens, there is a high pitched beep, the car cuts out and the Battery, Oil and Traction Control warning lights show. The car wont re-start for about 20 minutes, even tried bump starting. When it does re-start, it seems fine. The car has never been particularly hot when it happens and before anybody asks, it’s not the petrol
Sounds like a sensor problem to me. FFS don’t take it to a BMW dealer as they’ll rob you of at least 1k.
Think these are prone to sensor faults in the exhaust/cat system.
My suggestion is, find a local friendly mechanic, Flash the pearly whites, reveal a bit of cleavage, and plead poverty. They’re suckers for damsels in distress.
This seems to be an electrical fault, which could be caused by the heavy rain weve been having. DONT take it to BMW as they`ll charge you the earth just to have alook. There should be BMW specialists in your area who can do the same job as a dealer but for half the price.
My car isn`t a BMW but it did the same thing and it was the temp sensor which needed replacing.
It’s done it 3 times in the last week. Each time it happens, there is a high pitched beep, the car cuts out and the Battery, Oil and Traction Control warning lights show. The car wont re-start for about 20 minutes, even tried bump starting. When it does re-start, it seems fine. The car has never been particularly hot when it happens and before anybody asks, it’s not the petrol 
you nutter