If your auto transmission has been overfilled it may cause a problem. Transmissions that have too much transmission fluid may often exhibit shift problems and on some transmissions can cause excessive internal pressure. If its ignored this may cause damage or create leaks in your transmission. There is a difficulty that the transmission overfill presents. The majority of vehicle transmissions do not have a drain plug therefore it is not an easy task to correct the transmission fluid overfill problem. The cars transmission pan on the transmission may need to be removed to drain the transmission fluid or special equipment to purge the fluid from the transmission.