If your vehicle is showing door won't stay closed or pops open while driving, here are the most likely causes and the parts you'll need to fix each one.
The internal jaws or springs in the door latch mechanism have worn out or broken over time, preventing it from securely gripping the striker bar.
Hardened old grease, accumulated dirt, or ice (in winter) prevents the latch jaws from snapping shut and locking around the striker.
The door latch and the body striker do not line up perfectly, often due to loose bolts, recent bodywork, or improper adjustment, preventing the latch from fully engaging.
Worn hinge pins or bushings cause the heavy door to sag over time. This makes the latch hit the striker at a bad angle, preventing a secure secondary latch catch.
A stuck exterior or interior door handle, or a bound-up release cable, keeps constant tension on the latch mechanism, holding it in the released position.
An internal mechanical failure in the electronic lock actuator can jam the latch linkage, preventing the jaws from resetting to the closed position.