Possible reasons:
* Incorrect oil level: Check the gearbox oil level and add or drain excess oil if necessary.
* Incorrect oil type: Make sure you use the oil type recommended by the manufacturer.
* Contaminants in the oil: New oil can stir up existing contaminants and cause shifting problems. Try changing the oil again.
* Problems with sensors or solenoids: The transmission uses sensors and solenoids to control shifting. These components can fail and cause improper switching.
* Wear or damage to internal transmission components: Over time, transmission components can wear out or fail, which can lead to shifting problems.
* Mismatch between transmission computer and engine: In some cases, the transmission computer may not communicate correctly with the engine, resulting in shifting problems.
What to do:
*Check oil level: Check the oil level according to the instructions in the owner’s manual.
*Check Oil Type: Check your owner’s manual for the recommended oil type.
* Drain and change the oil again: This will help remove any contaminants that may have accumulated.
* Take your vehicle to a mechanic: If the problem is not related to oil levels or contamination, you may need a professional to diagnose and repair the transmission.