Throughout its service cycle, a tensioner ensures that the belt remains at the proper tension. Other components, such as the alternator and water pump, are also protected from undue stress and premature failure. Moreover, a tensioner is a relatively low-cost part to replace.

Drive belts last between 50,000 and 80,000 kilometers on average. Signs of a bad or failing drive belt tensioner are:

• Grinding or squeaking noise from the belt or tensioner
• Unusual belt wear
• Belt-driven accessories fail