2011 Chevrolet Avalanche Owner's Manual - Page 305

Driving and Operating 9-37 Engine Exhaust WARNING (Continued) . WARNING (Continued) If unusual fumes are detected or if it is suspected that exhaust is coming into the vehicle: . { WARNING Engine exhaust contains carbon monoxide (CO) which cannot be seen or smelled. Exposure to CO can cause unconsciousness and even death. Exhaust may enter the vehicle if: . The exhaust system leaks due to corrosion or damage. The vehicle exhaust system has been modified, damaged or improperly repaired. There are holes or openings in the vehicle body from damage or after market modifications that are not completely sealed. (Continued) . Drive it only with the windows completely down. Have the vehicle repaired immediately. . . The vehicle idles in areas with poor ventilation (parking garages, tunnels, deep snow that may block underbody airflow or tail pipes). The exhaust smells or sounds strange or different. (Continued) Never park the vehicle with the engine running in an enclosed area such as a garage or a building that has no fresh air ventilation. .