One of the most common reasons of gearbox failure is defective computer in the form of the gearbox controller. This element takes the form of a hydraulic switchboard with various sorts of valves, levers or bearings, all affecting the more or less reliable operation of the gearbox. The gearbox controller is therefore one of the most important elements of this component that is present in every motor vehicle. Its function is to control the transmission and feed it with oil under the correct pressure. The gearbox transmits power from the engine and thus affects the speed of the vehicle.