2008 Pontiac Grand Prix Owner's Manual - Page 299

If an overheat warning occurs without any sign of steam, try this for a minute or so: 1. In heavy traffic, let the engine idle in NEUTRAL (N) while stopped. If it is safe to do so, pull off the road, shift to PARK (P) or NEUTRAL (N) and let the engine idle. 2. Set the heater at the highest setting and the fan at the highest speed and open the windows as necessary. If the overheat warning no longer exists, the vehicle can be driven. Just to be safe, drive slower for about 10 minutes. If the warning does not come back on, the vehicle can be driven normally. If the warning continues, and you have not stopped, pull over, stop, and park the vehicle right away. If there is still no sign of steam, idle the engine for three minutes while parked. If the warning is still there, turn off the engine and get everyone out of the vehicle until it cools down. Also, see "Overheated Engine Protection Operating Mode" later in this section. You may decide not to lift the hood but to get service help right away. Overheated Engine Protection Operating Mode The overheated engine protection operating mode allows the vehicle to be driven to a safe place in an emergency situation. If an overheated engine condition exists, this protection mode alternates firing groups of cylinders to help prevent engine damage. In this mode, there will be a significant loss in power and engine performance. The engine coolant temperature gage indicator will move to the shaded area, and the engine coolant temperature warning light will come on, showing that an overheated engine condition exists. Driving extended miles (km) and/or towing a trailer in the overheated engine 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. 5-29