2000 GMC Envoy Owner's Manual - Page 267

Engine Air Cleaner/Filter 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: 1. To remove the air cleaner filter, remove the fasteners that hold the cover on. 2. Remove the cover and lift out the air filter. 3. Insert a new air filter, then replace the air cleaner cover. 4. Tighten the fasteners to hold the cover in place. 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. 6-15