GMC Yukon Owner's Manual page 455

3. Remove the engine air cleaner/filter from the
housing. Care should be taken to dislodge as little
dirt as possible.
4. Clean the engine air cleaner/filter sealing surfaces
and the housing.
5. Inspect or replace the engine air cleaner/filter.
6. Reinstall the cover and tighten the screws.
WARNING:
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 helps to stop
flames if the engine backfires. Use caution when
working on the engine and do not drive with the
air cleaner/filter off.
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