Cadillac 2010 CTS Sport Sedan Owner's Manual page 315

The engine air cleaner/filter is in the
engine compartment on the driver
side of the vehicle, near the front.
See
for more information
on location.
Inspect the air cleaner/filter at the
Maintenance intervals and replace
it at the first oil change after each
80 000 km (50,000 mile) interval.
See
for more information.
If you are driving in dusty/dirty
conditions, inspect the filter at each
engine oil change.
To inspect the air cleaner/filter,
remove the filter from the vehicle
and lightly shake the filter to release
loose dust and dirt. If the filter
remains caked with dirt, a new filter
is required.
To inspect or replace the engine
air cleaner/filter:
1. Turn the ignition off.
2. Remove the side cover by
pulling up on the front of the
cover.
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.