A carbon monoxide detector can save your life, but only if it's functioning properly. If you suspect your Kidde Nighthawk carbon monoxide alarm system isn't functioning as it should, run a quick series general troubleshooting diagnostics to check the device. You can also perform a test to verify that the CO sensor is working.
Check for the red blinking dot in the bottom-right corner of the LCD screen. If the dot is either not present or not blinking, unplug the unit, wait three minutes and plug the unit in again to reset it.
Press and hold the "Test/Reset" button to test the alarm. If the alarm portion is working properly, the LCD will display "888" and then display a number around 200. The Nighthawk will then issue four quick beeps, wait five seconds, and then issue four more beeps. It will then display "888" again. If any of these things do not occur, reset the device again.
Check the Low Battery indicator. If "Lb" displays on the screen, replace the unit's nine-volt battery.
Verify Sensor Functionality
Light an incense stick or cigarette, extinguish it, and then hold it 12 to 15 inches directly beneath the bottom air vents on the Nighthawk.
Keep holding it there for three to five minutes or until the CO alarm sounds. Do not hold the cigarette or incense too close or you may stain the unit.
Press the "Test/Reset" button when the CO alarm sounds. If it does not sound, the CO sensor may be malfunctioning and it should not be relied upon to provide accurate protection.