car turns off when it gets hot on 2005 BMW 645Ci

1st 2 times i experienced this was last october my car turned off in the middle of a highway and wouldnt turn back on after 20 min of driving. I took it to my mechanic he said he can't find anything wrong with it he reset the engine light. It's been sitting in my garage for a few month because of snow I took it out yesterday to test it out drove it for an hour it was driving great it didn't turn of but when I got off the high way on a red light it turned off it did this a few times till I got home.

by in Morton Grove, IL on February 21, 2011
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1 answer 1 comment
ANSWER by , February 21, 2011
Does your mechanic have the OE GT1 or similar diagnostic computer? Generic code readers won't work on this car. I'd take it to a BMW specialty shop and get a full system scan with a factory computer. I bet there are trouble codes registered in various modules which could help to resolve the problem. Zee
COMMENT by , February 22, 2011
Thanks for your reply Zeetech my mechanic specializes in European cars but I'm not sure what my mechanic is using to read the code but I was trying to avoid BMW dealer but I guess I just have to do it now.