First Alert Battery Carbon Monoxide Alarm | CO400

Manufacturer statement checked 23 Oct 2026 · source

“First Alert's page for the CO400 Battery-Operated Carbon Monoxide Alarm, read 2026-10-23: electrochemical CO sensor, one 9V battery, end-of-life warning, low-battery light and alarm, one button that silences the alarm and tests it, warranty 7 years limited. The CO400 user manual (BRK Brands, m08-0140-029) cites "Underwriters Laboratories Inc. Standard UL2034" for single and multiple station CO alarms. The manual also says "Replace alarm 5 years after installation" and gives an end-of-life signal about 7 years after installation (re-read 2026-10-26). UL's own listing directory was not checked, so UL 2034 is manufacturer-stated here. Amazon title reads "First Alert Battery Carbon Monoxide Alarm | CO400".”