Possible problems with the automatic transmission in a Chevrolet Aveo:
Doesn’t change gears:
*Low transmission fluid level
* Worn or damaged shift solenoids
*Transmission control module (TCM) malfunction
Gear slippage:
* Wear of friction discs and bands
*Low transmission fluid pressure due to leak or faulty pump
*TCM malfunction
Jerking or vibration when shifting gears:
* Worn or damaged transmission rubber seals (mounts)
* Faulty vehicle speed sensor
* Torque converter malfunction
Gear shift delay:
* Faulty engine speed sensor
* Faulty transmission fluid temperature sensor
*TCM malfunction
Extraneous noise during transmission operation:
*Low transmission fluid level
* Worn bearings or gears
* Torque converter malfunction
Other possible problems:
*Transmission fluid leak
* Contaminated transmission fluid
* Malfunction of the throttle position sensor
Possible reasons:
* Insufficient maintenance (for example, late replacement of transmission fluid)
* Using the wrong transmission fluid
* Wear or damage to internal transmission components
* Fault in the electrical system (such as faulty sensor or wiring)
Recommended actions:
* Check the level and condition of the transmission fluid.
* Scan the vehicle with a diagnostic scanner to identify trouble codes.
* Have your transmission problem diagnosed and repaired by a qualified mechanic.