In very cold weather, 0°F (-18°C) or colder or for higher altitudes (over 7,000 ft. or 2 135 m), the engine coolant heater can help you get easier starting and better fuel economy during engine warm-up. Usually, the coolant heater should be plugged in a minimum of four hours prior to starting your vehicle.

1. Turn off the engine.
2. Find the plug-in receptacle (either behind the front bumper or in the component box).
3. Plug a heavy-duty, three-prong extension cord (rated for at least 15 amps) into the vehicle's plug-in receptacle first. Then plug the extension cord into a normal, grounded 110-volt AC outlet.

Caution: Plugging the cord into an ungrounded outlet could cause an electrical shock. Also, the wrong kind of extension cord could overheat and cause a fire. You could be seriously injured. Plug the cord into a properly grounded three-prong 110-volt AC outlet. Use a heavy-duty three-prong extension cord rated for at least 15 amps.

4. Before starting the engine, be sure to unplug the cord.

How long should you keep the coolant heater plugged in? The answer depends on the outside temperature. From 32°F to -10° F (0°C to -23°C), keep the coolant heater plugged in at least two hours. Below -10°F (-23°C), keep the coolant heater plugged in for a minimum of eight hours or overnight. It will not harm either the coolant heater or the vehicle to leave the coolant heater plugged in longer than the times stated. See What Fuel to Use for information on what fuel to use in cold weather.