Premature failure can occur as a direct result of a number of things. The failure of another element in the drive can directly affect the OAP. Excessive starting and idling times can reduce OAP lifetime. A worn OAP will generate belt vibration / drive noise / component wear that will eventually lead to failure. A broken, damaged or missing dust cap can result in failure of the OAP. As the OAP is designed to absorb engine speed fluctuations, it wears. It should be noted that some applications are more sensitive to OAP failure than others.