---
product_id: 353563489
title: "CO400 Carbon Monoxide (CO) Detector, Battery Operated Alarm, 1-Pack"
brand: "first alert"
price: "€ 46.95"
currency: EUR
in_stock: true
reviews_count: 5
category: "First Alert"
url: https://www.desertcart.nl/products/353563489-co400-carbon-monoxide-co-detector-battery-operated-alarm-1-pack
store_origin: NL
region: Netherlands
---

# 85 dB loud alarm 5-year battery life Advanced electrochemical sensor CO400 Carbon Monoxide (CO) Detector, Battery Operated Alarm, 1-Pack

**Brand:** first alert
**Price:** € 46.95
**Availability:** ✅ In Stock

## Summary

> 🚨 Stay ahead of danger with silent tech that speaks loud when it counts!

## Quick Answers

- **What is this?** CO400 Carbon Monoxide (CO) Detector, Battery Operated Alarm, 1-Pack by first alert
- **How much does it cost?** € 46.95 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.nl](https://www.desertcart.nl/products/353563489-co400-carbon-monoxide-co-detector-battery-operated-alarm-1-pack)

## Best For

- first alert enthusiasts

## Why This Product

- Trusted first alert brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Instant Loud Alert:** 85-decibel alarm cuts through noise to alert you immediately when CO levels become dangerous.
- • **Precision Detection Tech:** Equipped with an advanced electrochemical sensor for the most accurate carbon monoxide readings in any room.
- • **Trusted Longevity & Support:** 5-year sensor lifespan backed by a limited warranty and end-of-life signal for timely replacement.
- • **Effortless Setup & Placement:** Compact, no-install design with optional wall mount lets you protect every level and bedroom with ease.
- • **Uninterrupted Safety Anywhere:** Battery-powered design ensures continuous CO monitoring even during power outages—no wiring needed.

## Overview

The First Alert CO400 is a battery-operated carbon monoxide detector featuring a 5-year electrochemical sensor and an 85 dB alarm. Its compact, no-install design allows flexible placement anywhere in your home, providing reliable, continuous CO monitoring even during power failures. Trusted since 1958, it offers peace of mind with easy testing, audible alerts for battery replacement, and a 5-year limited warranty.

## Description

The First Alert CO400 carbon monoxide alarm uses an electrochemical sensor the most accurate technology available. The permanent sensor lasts up to 5 years. It is powered by a 9V replaceable battery giving you peace of mind even during power outages. The test/silence button silences the alarm and allows you to test its functionality. The unit monitors and re alarms if carbon monoxide level persist sounding a loud 85 decibel horn. No installation is required and the attractive design allows the unit to be placed anywhere you need it. It includes an optional wall mount with no outlet required. An audible and visual battery signal alerts you to replace the battery. Pull down action chart has convenient guide on what to do if an alarm sounds. 5 year limited warranty. Ul listed.

Review: I bought two of the First Alert Carbon Monoxide Detectors (model CO400), and I’m very happy with them. They were super easy to install — no outlet needed since they run on batteries. I just mounted them on the wall, and they were ready to go in minutes.I like that the battery operation means I can place them anywhere in my home without worrying about finding a plug. The alarm is loud enough to hear clearly, and the design is compact and simple.It gives me peace of mind knowing my family is protected. Overall, great value, easy setup, and reliable safety product. Highly recommend!
Review: I purchased this alarm to install in the upstairs hallway between bedrooms. It was very easy to install and works perfectly and provides the added security I required. I was surprised and happy at how quickly the parcel arrived!

## Features

- Keep your family safe with this easy to use, battery operated carbon monoxide alarm; Battery powered alarms provide continuous monitoring of CO levels, even if there's a power failure
- Features an advanced electrochemical carbon monoxide sensor that accurately detects carbon monoxide levels, no matter where the detector is placed in the room.The alarm sequence should last 5-6 seconds. If it does not alarm, make sure fresh batteries are correctly installed, and test it an. If the unit still does not alarm, replace it immediately
- A loud 85 decibel alarm sounds when CO levels reach dangerous levels
- To ensure complete protection make sure to place one on each level of your home and in each bedroom
- 5-year limited warranty; Equipped with end of life signal chirp, so you know when it’s time to replace the unit for safety.All first alert CO alarms are rigorously tested to meet UL standards.First Alert has been the most trusted brand in home safety since launching the first residential smoke alarm in 1958 (Based on a First Alert Brand Trust Survey in February 2018)

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B000N8OYXI |
| Best Sellers Rank | #12,349 in Tools & Home Improvement ( See Top 100 in Tools & Home Improvement ) #8 in Carbon Monoxide Detectors |
| Department | Electronics |
| Item model number | CO400 |
| Manufacturer | First Alert |
| Product Dimensions | 12.7 x 2.54 x 7.62 cm; 204.12 g |

## Product Details

- **Brand:** First Alert
- **Colour:** White
- **Power source:** Battery Powered
- **Product dimensions:** 2.5D x 12.7W x 7.6H centimeters
- **Style:** Battery Powered

## Images

![CO400 Carbon Monoxide (CO) Detector, Battery Operated Alarm, 1-Pack - Image 1](https://m.media-amazon.com/images/I/51RBX7hitxL.jpg)

## Questions & Answers

**Q: Has anyone else received the CO400 with one 9 volt battery instead of the  two AA batteries listed in description and on picture of packaging display?**
A: Yes, Received the 9-Volt battery version.  I live in California.
I'm not a lawyer but my research shows that in California Smoke detectors and Combo Smoke/Carbon detectors must come with a 10 year lifespan battery.  This law does not seem to apply to devices that only detect Carbon Monoxide like that one for sale here.

**Q: Why can't this be purchased in or shipped to California?**
A: I live in California. Yes, I received the 9-Volt battery version.
I'm not a lawyer but my research shows that in California Smoke detectors and Combo Smoke/Carbon detectors must come with a 10 year lifespan battery.  This law does not seem to apply to devices that only detect Carbon Monoxide like that one for sale here.

**Q: the package  picture shows 9-volt, but sounds like it is a crapshoot on what they will send you.  which is better and lasts longer, 2AA or 1 9V?  I hate taking out and putting in 9v batteries.  so many to choose from. would prefer plug-in but would be too low.**
A: I bought a package of AA batteries because this item description said it takes 2 AA. It does not. It takes (and comes with) one 9V. This is model CO400.

**Q: Red light is on. Is that normal?  Tested and it chirps with test.  Also checked battery.**
A: YEs, red light is normal.  If red light blinks - read manufacturer's guide in link below.  

https://www.brkelectronics.com/pdfs/2017/10/23/803bf30c.pdf

## Customer Reviews

### ⭐⭐⭐⭐⭐ Review
*by S***N on 12 November 2025*

I bought two of the First Alert Carbon Monoxide Detectors (model CO400), and I’m very happy with them. They were super easy to install — no outlet needed since they run on batteries. I just mounted them on the wall, and they were ready to go in minutes.I like that the battery operation means I can place them anywhere in my home without worrying about finding a plug. The alarm is loud enough to hear clearly, and the design is compact and simple.It gives me peace of mind knowing my family is protected. Overall, great value, easy setup, and reliable safety product. Highly recommend!

### ⭐⭐⭐⭐⭐ Review
*by A***R on 17 December 2016*

I purchased this alarm to install in the upstairs hallway between bedrooms. It was very easy to install and works perfectly and provides the added security I required. I was surprised and happy at how quickly the parcel arrived!

### ⭐⭐⭐⭐⭐ Review
*by M***S on 20 January 2026*

Works great, looks good. Definitely recommend. Great deal for the price.

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*Product available on Desertcart Netherlands*
*Store origin: NL*
*Last updated: 2026-02-16*