Mechanical problems:
* Friction discs are worn or dirty
* Malfunctions of the torque converter (donut)
* Worn or damaged transmission gears and bearings
*Transmission fluid leak
Electrical problems:
* Malfunction of solenoids that control gear shifting
* Damage to wiring or connectors
* Malfunction of sensors providing information about the speed and position of gears
Hydraulic problems:
*Low or contaminated transmission fluid
* Malfunction of the oil pump or distribution unit
* Clogged channels and filters in the hydraulic system
Software problems:
* Malfunctions in the software that controls the gearbox
* Incorrect settings or software updates
* Software mismatch with specific gearbox model
Other reasons:
* Transmission overheating due to heavy use or insufficient cooling
* Improper maintenance or replacement of transmission fluid
* Using the wrong transmission fluid
* Overloading the vehicle or towing too heavy loads