Cadillac 2011 CTS Coupe Owner's Manual page 338

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
scheduled maintenance intervals
and replace it at the first oil change
after each 80 000 km (50,000 mile)
interval. See
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 covered with dirt, a new
filter is required.
To inspect or replace the engine air
cleaner/filter:
1. Turn the ignition off.
for more
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.