2006 GMC Yukon Owner's Manual - Page 404

Overheated Engine Protection Operating Mode If an overheated engine condition exists and the REDUCED ENGINE POWER message is displayed, an overheat protection mode which alternates firing groups of cylinders helps prevent engine damage. In this mode, you will notice a loss in power and engine performance. This operating mode allows your vehicle to be driven to a safe place in an emergency. Driving extended miles (km) and/or towing a trailer in the overheat protection mode should be avoided. Notice: After driving in the overheated engine protection operating mode, to avoid engine damage, allow the engine to cool before attempting any repair. The engine oil will be severely degraded. Repair the cause of coolant loss, change the oil and reset the oil life system. See Engine Oil on page 5-15. Cooling System When you decide it is safe to lift the hood, here is what you will see: 8.1L V8 Engines A. Coolant Surge Tank B. Coolant Surge Tank Pressure Cap C. Engine Cooling Fan 5-30