Cadillac 2002 DeVille Owner's Manual page 328

Follow these steps to reinstall the cover to the engine air
cleaner/filter housing:
1. Align the three tabs located on the back of the cover
with the three slots on the back of the housing.
2. Push the cover slightly down and towards the
engine to engage the tabs in the slots and align the
two wing screws.
3. Engage and tighten the two wing screws on the top
of the engine air cleaner/filter housing cover.
Refer to the Maintenance Schedule to determine when to
replace the air filter.
See "Scheduled Maintenance Services" in the Index.
6-18
CAUTION:
Operating the engine with the air cleaner/filter
off can cause you or others to be burned. The air
cleaner not only cleans the air, it stops flame if
the engine backfires. If it isn't there, and the
engine backfires, you could be burned. Don't
drive with it off, and be careful working on the
engine with the air cleaner/filter off.
NOTICE:
If the air cleaner/filter is off, a backfire can
cause a damaging engine fire. And, dirt can easily
get into your engine, which will damage it.
Always have the air cleaner/filter in place when
you're driving.