How long do carbon monoxide detectors last?

Most CO sensors are rated for the life of the unit, commonly 7 to 10 years, after which the entire detector should be replaced. Several picks here advertise 10-year sealed batteries, while plug-in models with AA backup require periodic battery checks. Verified-purchase reviewers across listings frequently mention end-of-life chirping as a sign it's time to replace, so note the manufacture date on the back.