What is a nader pin on an automobile door?

A Nader pin (commonly called a door check pin or door hinge pin) is a small metal pin used in an automobile door mechanism to limit how far the door opens and to hold the door in position.

It helps prevent the door from swinging too wide, protects the hinges, and reduces the risk of damage from strong wind or uneven parking surfaces. Over time, a worn or broken Nader pin can cause the door to sag, make noise, or not stay open properly.