GMC Sierra Owners Manual
Overheated Engine Protection Operating Mode
If an overheated engine condition exists and the ENGINE POWER IS REDUCED message displays, an overheat protection mode which alternates firing groups of cylinders helps to prevent engine damage. In this mode, a loss in power and engine performance will be noticed.
This operating mode allows the vehicle to be driven to a safe place in an emergency. Driving extended km (mi) 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 10‑7.