WARNING: This page is about a different car, the 2003 Pontiac Aztek and 2003 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
Remove the rubber grommets.
Clean the valve rocker arm cover.
Inspect the valve rocker arm cover for damage.
Replace the valve rocker arm cover if necessary.
Fig 1: Inspecting Valve Rocker Arm Cover For Damage