I was driving over an overpass on to the free way. It was about 11am. The steering wheel locked in a turning position, driving the car off the overpass. I was able to yank the wheel and get it back straight. The auto pilot was not on, the cruise control was not on. I drove it straight to the service center, i though i should call so i put the car in curise control to pull out my phone but decided against it and turned it off at 11:15. Now the service center says they can not duplicate it they are telling me nothing is wrong. This has never happened before. I have never had any issues with my car.