If you disclosed in writing to the dealership that you traded your car in for the problems that you were having with it and provided the paper work concerning the repairs, then you should not be responsible for any problems with it that may have later occurred.The car repair facility that did the work may have an issue. However, if you did not disclose such material information before the trade in then you may have some issues raised by the dealership.Personally, for the car dealership to have accepted the car as a trade in sight unseen was poor judgment by its representative who was handling the transaction.