Mechanical faults:
* Wear of friction discs and steel plates
* Damage to gears, bearings or synchronizers
* Leaking or low transmission fluid level
* Clogged oil filter or channels
* Damage or wear to speed sensors
Electrical and electronic faults:
*Damage to shift solenoids
* Faulty gear selector position sensor
* Malfunction of the electronic control unit (ECU)
* Damaged or corroded wiring
Hydraulic faults:
* Pump wear or malfunction
* Clogged or damaged valve body
* Leaks or low pressure in the hydraulic system
Other reasons:
* Improper use or maintenance (such as towing excessive loads or overheating)
* Exposure to external factors (for example, shocks, water ingress)
*Normal wear and tear
External factors contributing to malfunctions:
* Contaminated transmission fluid
* Aggressive driving style
* Towing heavy loads
* Lack of regular maintenance (eg fluid and filter changes)