Possible reasons:
1. Transmission fluid level is low:
* Check the fluid level and add if necessary.
2. Contaminated transmission fluid:
* Replace transmission fluid and filter.
3. Solenoid valves:
*Solenoid valves may be faulty and cause shifting problems.
4. Hydraulic unit:
* The valve body may be dirty or defective.
5. Throttle Position Sensor:
* A faulty throttle position sensor can cause problems transmitting a signal about the amount of air entering the engine.
6. Vehicle speed sensor:
*A faulty speed sensor can cause shifting problems.
7. Transmission Control Module (TCM):
*TCM may be faulty.
8. Torque converter:
* The torque converter may be faulty, causing the engine to lock up.
9. Spark plugs or ignition coils:
* Faulty spark plugs or ignition coils can cause misfire, which can cause the engine to stall.
10. Dirty air filter:
*A dirty air filter can result in an incorrect air/fuel mixture, which can cause the engine to stall.
Diagnostics:
* Connect the scanner and read the fault codes.
* Check the transmission fluid level and condition.
* Check wiring and connectors for damage.
* Inspect the valve body for dirt or damage.
* Check the throttle position and vehicle speed sensors.
* Check the spark plugs and ignition coils.
* Replace the air filter.