Possible reasons:
1. Low level or poor quality gear oil:
* Check the transmission oil level and add if necessary.
* Use oil recommended by the manufacturer.
2. Faulty sensors:
*Camshaft Position Sensor
* Crankshaft position sensor
* Throttle Position Sensor
3. Malfunction of automatic transmission solenoids:
* Solenoids control the hydraulic flow inside the automatic transmission. Faulty solenoids can cause shifting problems.
4. Problems with the torque converter:
* The torque converter transfers power from the engine to the automatic transmission. A faulty torque converter can cause the transmission to slip and stall the engine.
5. Wiring problems:
*Damaged or exposed wires can cause problems with signals from sensors and solenoids.
6. Malfunction of the automatic transmission electronic control unit (TCU):
* The TCU controls the automatic transmission operations. A faulty TCU can cause a variety of shifting problems.
7. Mechanical problems with automatic transmission:
* Worn or broken clutches
* Worn gears
* Faulty bearings
What to do:
* Check transmission oil level and condition.
* Scan the vehicle for trouble codes that may indicate a bad sensor or solenoid.
*Consult a qualified mechanic for diagnosis and repair. Do not attempt to repair an automatic transmission yourself unless you have the appropriate skills.