GMC 2004 Sierra 1500 Pickup Owner's Manual page 424

1. Loosen the screws on the cover of the housing and
lift up the cover.
2. Remove the air cleaner/filter from the housing. Care
should be taken to dislodge as little dirt as possible.
3. Clean the filter sealing surface and the housing.
4. Install the new engine air cleaner/filter.
5. Reinstall the cover and tighten the screws.
6. Reset the filter change indicator, if equipped, by
pressing the top button on the indicator.
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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 helps to
stop flame if the engine backfires. If it is not
there and the engine backfires, you could be
burned. Do not 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
are driving.