Cadillac 2012 CTS Owner's Manual page 328

3. Disconnect the electrical
connector from the air box.
4. Loosen the screw on the clamp
holding the air outlet duct in
place. Do not remove the clamp.
Move the duct aside.
5. Remove the hose from the air
cleaner housing mounting arm.
Move the hose aside.
6. Remove the three air cleaner
housing cover screws.
7. Move the air cleaner housing
cover and remove the cover
from the air cleaner housing.