A good gearbox is quiet and shifts gears without resistance. If any of the following symptoms appear during the vehicle's operation, you can be sure that something is wrong with the transmission.

You will need diagnostics in the following cases:

• the gearbox starts to make strange sounds;
• fluid leaks;
• gear shifting is incorrect or untimely.

With timely maintenance and proper operation, any modern automatic transmission is very reliable. It is important to understand the following: due to the design features and the greater complexity of the components than in a manual transmission, malfunctions with it happen more often.
Repair of this unit is usually necessary due to the wear of the entire structure or its individual components. In addition, the box fails due to too old or contaminated oil, as well as due to the high mileage of the car in excess of that guaranteed by the manufacturer.
The most common automatic transmission failure is associated with damage to this element while driving. Also, seal elements often fail, which cause oil leakage. Because of this, the pressure in the system drops, after which the heat shields burn out.