Kidde is recalling certain Kidde NightHawk combination smoke/carbon monoxide (CO) alarms. The alarm can fail to continue to chirp when it reaches its seven-year end of life if the batteries are replaced, leading consumers to believe it is still working. This poses a risk of consumers not being alerted to a fire or CO incident in their home. Kidde recommends replacing the affected units.
See more here:
https://www.cpsc.gov/Recalls/2017/Kidde-Recalls-Combination-Smoke-CO-Alarms