* Worn or damaged synchronizer rings. The synchronizer rings in a transmission help to match the speeds of the input and output shafts so that they can engage smoothly. If the synchronizer rings are worn or damaged, they may not be able to do their job properly, which can cause the transmission to pop out of gear.
* Bent or damaged shift fork. The shift fork is the part of the transmission that moves the gears into place. If the shift fork is bent or damaged, it may not be able to move the gears into place properly, which can also cause the transmission to pop out of gear.
* Low transmission fluid level. If the transmission fluid level is low, it may not be able to properly lubricate the gears and other moving parts in the transmission. This can cause the gears to wear out prematurely and also lead to the transmission popping out of gear.
* Defective shift cable. The shift cable is the part of the transmission that connects the shift lever to the transmission. If the shift cable is defective, it may not be able to move the gears into place properly, which can also cause the transmission to pop out of gear.
To diagnose the exact cause of your problem, you will need to have your car inspected by a qualified mechanic.
