Drunk Driving Statute Of Limitations

i am from orange county california in june 1994 my sister was arrested for dui on the 55 newport beach fwy.it was determined at that time that she was not legally drunk and was released.she recently received a notice from orange county court to appear before a judge concerning her drunk driving arrest.i told her she should talk to a attorney before she goes to court so she doesn't get blindsided.the question i have is there a statute of limitations on dui charges. p.s.she called the d.a. and they have no record of the court order.