I work in software and since cars are now a series of complex computers and code...they have the same problem that all the other software I work on does. They are complex systems with virtually no debugging or logging built in to detect unexpected (and faulty) behavior. So the poor service tech (which is me at my software company) stand there, scratch my head and tell the user "I couldn't recreate the problem." Designers never think anything will ever go wrong and aren't given time to build in debugging..
OK, I feel better now.