First alert smoke and carbon monoxide alarm 4 beeps

To warn of dangerous CO levels, most detectors will beep 4 or 5 times in a row about every 4 seconds. Do not mistake dangerous levels of poisonous gas for a detector with low battery!

3 chirps (about 1x per minute): Malfunction chirp Replace with a new alarm as soon as possible. Check to ensure that your alarm is not expired and in need of replacement. If it's still under warranty, return alarm to the manufacturer for replacement.

Here's a simple guide: Smoke alarms alert you with three beeps in a row. Carbon monoxide alarms alert you with four beeps. A single chirp means the battery is low or the detector should be replaced.

Check for bugs, debris, or dust in the sensing chamber. The inside of the alarm might have been triggered by hidden dust, dirt, or spiderwebs. Regular cleaning prevents most nuisance alarms. Clean the detector with a can of compressed air and your vacuum's soft brush attachment, and reinstall the alarm.