Cadillac 2007 DTS Owner's Manual page 214

2. Then, insert a tool behind the push pin
located on the inboard side of the air
filter compartment to carefully pry the pin out.
214
3. To remove the air filter, insert a tool between
the air filter and the compartment wall on the
outboard side of the vehicle. Then, push
in to flatten the pin holding the air filter
in place. Gently remove the air filter and any
loose debris that may be inside the air
filter compartment.
4. Insert the new air filter by pushing until you
hear a click. Then, reinstall the push pin and
snap the cover into place.