2007 Nissan Sentra Owner's Manual - Page 130

Alarm and warning when the engine starts When the Intelligent Key system warning light ( ) blinks red and the outside buzzer sounds, make sure the Intelligent Key is inside the vehicle. Warning for low battery power When the Intelligent Key battery is low, the Intelligent Key system warning light ( ) will blink green for about 30 seconds after the ignition switch is turned to the ON position. This warning is to let you know that the battery of the Intelligent Key will run down soon. Replace it with a new one. Refer to "Battery replacement" in the "Maintenance and do-it-yourself" section. NISSAN recommends replacing the battery at a NISSAN dealer. Preventing the Intelligent Key from being left in the vehicle If you lock all doors using the power door lock switch with the Intelligent Key in the vehicle, all of the doors unlock immediately and the buzzer will warn you when the door is closed. 3-20 Pre-driving checks and adjustments