When to change the serpentine chain on 2004 gmc envoy?

The serpentine belt on a 2004 GMC Envoy should typically be inspected every 30,000 to 60,000 miles and replaced if there are signs of wear, such as cracks, fraying, or glazing. If you hear squeaking or chirping noises from the engine bay, it may indicate that the belt is slipping and should be replaced. Additionally, if the belt has been in use for more than five years, it's advisable to replace it as a preventive measure, regardless of its appearance. Always refer to the owner's manual for specific recommendations.