The pitman arm of BMW is nothing but its steering component. Basically, the steering wheel of the car needs linear motion. But the sector shaft produces angular motion. It is the pitman arm that does the conversion of angular motion to linear motion. A faulty pitman arm leads to poor steering and steering instability. As poor steering can be death-dealing, hence, it is imperative to keep the pitman in good working condition. When the pitman arm shows the signs of failure, replace the component straightaway by consulting an adept BMW technician.