How do you change the serpentine belt tensioner on 2004 Pontiac vibe?

To change the serpentine belt tensioner on a 2004 Pontiac Vibe, first, ensure the engine is off and cool. Use a socket wrench to relieve tension on the tensioner pulley, then remove the serpentine belt from the tensioner. Unbolt the old tensioner from its mount, replace it with the new tensioner, and reattach the serpentine belt following the correct routing. Finally, check the tensioner’s operation before starting the engine.