check engine and speedometer stops working on 1995 Buick LeSabre

when at opperating temp., the check engine light comes on and the speedometer stops working and also there is no first gear or overdrive. I was told it was a transmission solenoid and also it could be a speed sensor. anyone else have this problem, and if so, what the heck was it? I really do not want to put a lot of money into a 15 year old car even though i do like its comfort and ride. Thanks in advance!

Asked by for the 1995 Buick LeSabre
the sensor that sends the vehicle speed to the ecm is not functioning correctly. either the sensor is bad or the plastic driven gear is dished from age. if this is the case. it is a easy fix and not to expensive.