One of the most common symptoms of a failing control arm is a knocking noise coming from the suspension. This is caused by the loose control arm bushings which allow the control arm to move around more than it should. Another symptom is uneven tire wear, as a failing control arm can cause the wheel to be misaligned. This will cause one side of the tire to wear down more quickly than the other. Finally, a bad control arm can also cause your car to pull to one side while driving.