1. Low Transmission Fluid: If the transmission fluid level was low, it could cause the transmission to slip and not shift properly. Make sure to check the transmission fluid level and add more if necessary.
2. Faulty Transmission Filter: A clogged or dirty transmission filter can restrict the flow of fluid and cause the transmission to shift erratically. Replace the transmission filter if it is dirty or clogged.
3. Faulty Shift Solenoid: The shift solenoid is responsible for engaging and disengaging the transmission gears. If the shift solenoid is faulty, it can cause the transmission to shift improperly. Have the shift solenoid tested and replaced if necessary.
4. Faulty Transmission Control Module (TCM): The TCM is the computer that controls the transmission. If the TCM is faulty, it can cause the transmission to shift erratically. Have the TCM tested and replaced if necessary.
5. Internal Transmission Damage: If the transmission has sustained internal damage, it may not shift properly and may require rebuilding or replacement.
