First Alert CO605 Plug-In Carbon Monoxide Detector
- Power Source: Corded Electric
- Sensor Type: Electrochemical
- Alarm: Carbon Monoxide
- Operating Humidity: 10-95% RH
Last refreshed Sep 8, 2026 · Based on the Amazon listing and published specifications, not hands-on testing.
The middle-tier First Alert plug-in: real outage protection from the battery backup, at a lower cost than the display-and-gas combo unit.
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ASIN: B000ND74XAModel: CO605Category: Carbon Monoxide Detectors
Overview
A plug-in carbon monoxide detector with battery backup, a single test and mute button, and UL-tested electrochemical sensing. Measures 3.4 by 1.38 by 5 inches and carries a 7 year limited warranty.
This sits between the CO600 and the GCO1CN: it adds the battery backup the CO600 lacks, without the digital display or gas detection of the combination unit. First Alert lists it as UL tested, with a mute button that quiets a low battery chirp for up to 8 hours instead of forcing an immediate swap.
- Plug-in with battery backup
- UL tested electrochemical sensor
- One button test and mute
- 7 year limited warranty
Who it's for
Homeowners who want plug-in CO coverage that keeps working through a power outage, without paying for the digital display or added gas sensing of the combination model.
Pros and cons
- Battery backup keeps monitoring through a power outage
- Single button covers both test and mute
- Low battery chirp can be muted for up to 8 hours
- UL tested electrochemical sensor
- No digital display of CO levels
- No gas detection beyond carbon monoxide
Performance notes
The electrochemical sensor monitors continuously while plugged in, and the battery backup takes over automatically if the outlet loses power. A single button both tests the alarm and mutes nuisance triggers, and a low battery chirp can be silenced for up to 8 hours at a time rather than needing an immediate fix. First Alert states all its CO alarms are tested to UL standards.
Specifications
| Brand | First Alert |
|---|---|
| Model | CO605 |
| Dimensions & fit | |
| Item Weight | 0.26 pounds |
| Item Dimensions D X W X H | 1.4 × 5 × 3.4 inches |
| Capacity & performance | |
| Upper Temperature Rating | 105 °F |
| Power & efficiency | |
| Power Source | Corded Electric |
| Construction & materials | |
| Enclosure Material | Plastic |
| Color | White |
| Compatibility & installation | |
| Compatible Devices | Standalone Wall Outlet |
| Included components | |
| Unit Count | 1 |
| Warranty & support | |
| Manufacturer Warranty Description | 7-Year Limited Warranty |
| Other details | |
| Sensor Type | Electrochemical |
| Alarm | Carbon Monoxide |
| Operating Humidity | 10-95% RH |
| Number Of Items | 1 |
| Product Style | Plug In Alarm With Battery Backup |
| Mfr Part Number | FATCO605 |
| Builtin Media | Alarm, Battery |
| Item Type Name | CO Alarm |
Frequently asked questions
Does this model have a display?
No, it alarms at the 85 decibel threshold rather than showing a running CO ppm number.
What happens with the low battery chirp?
The mute button can silence a low battery signal for up to 8 hours at a time.
What size is the unit?
First Alert lists it at 3.4 inches long, 1.38 inches wide and 5 inches tall.