GMC 2008 Envoy - Manual (Page 316)

How to Inspect the Engine Air
Cleaner/Filter
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 caked with dirt, a new filter is
required.
To inspect or replace the engine air cleaner/filter, do the
following:
1. Remove the screws on the engine air cleaner/filter
and lift off the cover.
2. Remove the air cleaner/filter from the housing. Care
should be taken to dislodge as little dirt as possible.
3. Inspect or replace the engine air cleaner/filter.
4. Reinstall the cover and tighten the screws.
{ 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 flames 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.
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