A CV boot (Constant Velocity boot) is a protective cover which fits snugly over the CV joint in order to protect it from debris and damage when the vehicle is in motion. It contains a lubricant which enables the parts of the CV joint to move smoothly without wear. Most CV boots are made of either plastic or rubber.
Failures in a CV boot are most likely caused by damage to the plastic or rubber material which can mean that the essential lubricant is lost and contaminants can enter the boot. This causes risk to the CV joint, which is essential in driving the vehicle forward as it transfers torque from the transmission to the wheels at a constant speed.
The most common way to diagnose a damaged CV boot is by inspection by a mechanic who will be able to see the cracked and damaged boot. However, in the event of a damaged CV boot causing damage to the CV joint you may hear a popping or clicking noise when turning, particularly when accelerating or feel shuddering or sideways shaking of the vehicle during acceleration. This issue should be rectified immediately.