Where are spark plugs located on 2005 Chevy Cobalt?

The spark plugs on a 2005 Chevy Cobalt are located on the top of the engine, under a plastic cover (often called a valve cover). To access them, you'll need to remove this cover. They're arranged one per cylinder, and the exact location within that area will depend on whether it's a 2.0L or 2.2L engine. A repair manual or online diagram specific to your engine size will show the precise locations.