Chevrolet 2007 Cobalt Owner's Manual page 324

The adjustment screw can be turned with a 6 mm
socket wrench.
324
To adjust the vertical aim on the headlamps, do
the following:
1. Open the hood. See Hood Release on
page 283 for more information.
2. Locate the aim dot on the lens of the
low-beam headlamp.
3. Measure the distance from the ground to the
aim dot on the low-beam headlamp. Record
the distance.