Whenever a fault is observed it is mandatory to determine if the fault is electrical or mechanical or hydraulic in order to think of repairing it. Diagnosis is done by requiring specific understanding of how the transmission works and how it is built, as well as the availability of sophisticated testing equipment; problems with the automatic transmission should therefore be evaluated by a dealer service department or any other qualified repair shop. Furthermore, a faulty transmission should not be pulled out of the car until the car was diagnosed by a competent mechanic with the right tools for troubleshooting, as the diagnosis of the transmission and its components is most effectively, as well as only possible with the transmission mounted in the car.