Audi, now owned by fellow German automaker Volkswagen, has been making cars since 1910. The serpentine belt on the front of your Audi's engine, like all serpentine belts, is a single belt that operates all of the front engine accessories. On the Audi, the tension in the serpentine belt is maintained by an automatic belt tensioner. You should replace the serpentine belt if shows excessive cracking within the ribs on the inside of the belt.

Open the bonnet on the Audi and locate the routing diagram for the serpentine belt. The diagram is located on the top of the plastic cover that surrounds the radiator.

Locate the automatic belt tensioner, located on the left-hand side of the alternator. Use the square hole in the spring-loaded arm of the tensioner to loosen the serpentine belt.

Insert the end of the 3/8-inch drive breaker bar into the square hole of the tensioner. Turn the tensioner clockwise. Pull the belt off the tensioner pulley.

Pull the belt out of the other pulleys and out of the engine bay. Route the new serpentine belt into each of the accessory pulleys. Use the routing diagram on the top of the fan shroud for the routing instructions.

Turn the automatic belt tensioner clockwise again with the breaker bar. Slide the belt under the tensioner pulley and release the tensioner. Remove the breaker bar and make sure that the new belt is properly routed around the pulleys.

Crank the Audi and let it run for approximately 30 seconds. Turn the motor off and inspect the belt again to make sure that the belt is still centred inside of each pulley. Close the bonnet.