2003 GMC Sonoma Owner's Manual - Page 294

If Steam I Coming From Your Engine s Steam from an overheated engine can burn you badly, even if you just open the hood. Stay away from the engine if yousee or hear steam coming from it. Just turn it off and get everyone away from the vehicleuntil it cools down. Wait until there is no sign of steam or coolant before you open the hood. If you keep driving when your engine is overheated, the liquids in it can catch fire. You or others could be badly burned. Stop your engine if it overheats, and get out of the vehicle until the engineis cool. Notice: If your engine catches fire because you keep driving with no coolant, your vehicle can be badly damaged. The costly repairs would not be covered by your warranty. 5-31