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First Alert CO400 Carbon Monoxide (CO) Detector, Battery Operated Alarm, 1-Pack

4.7 4.7 out of 5 stars 19,143 ratings

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Pack of 1
Detector

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About this item

  • 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 again. If the unit still does not alarm, replace it immediately
  • A loud 85 decibel alarm sounds when CO levels reach dangerous , Battery Replaceable - Yes
  • 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)
See more product details

Customer ratings by feature

Easy to read
4.5 4.5
Easy to install
4.5 4.5
Accuracy
4.4 4.4
Value for money
4.3 4.3

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From the manufacturer

First Alert
What is carbon monoxide?

Common sources of Carbon Monoxide

Furniture

Dryer Vent

Chimney

What does the beep mean?

4 beeps and a pause

1 beep every minute

5 beeps every minute

Emergency: Carbon monoxide has been detected. Move to fresh air and call 911.

Low battery: It's time to replace the batteries in your carbon monoxide alarm.

End of life: It's time to replace your carbon monoxide alarm.

Recommended alarm placement

Looking for specific info?

Product information

Technical Details

Additional Information

Warranty & Support

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First Alert CO400 Carbon Monoxide (CO) Detector, Battery Operated Alarm, 1-Pack


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Product guides and documents

Product Description

Product 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.

Amazon.com

Carbon monoxide (CO) is the leading cause of accidental poisoning deaths in America, yet many people don't know they are suffering from CO poisoning until its too late. Since symptoms of CO poisoning are like the flu, you might not even know you're in danger at first. That's why a carbon monoxide alarm is an excellent way to protect your family. It can detect the CO you can't see, smell or taste in the air. The First Alert CO400 carbon monoxide alarm uses an electrochemical carbon monoxide sensor-the most accurate technology available. The permanent sensor lasts up to five years. It is powered by on 9V replaceable battery giving you peace of mind even during power outages. The test/silence button both silences the alarm and allows you to test its functionality. The unit monitors and re-alarms if carbon monoxide levels 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 low 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. --Bree Norlander

WARNING:

CHOKING HAZARD -- Small parts. Not for children under 3 yrs.

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First Alert CO400 Carbon Monoxide (CO) Detector, Battery Operated Alarm, 1-Pack
FIRST ALERT First Alert CO400 Carbon Monoxide (CO) Detector, Battery Operated Alarm, 1-Pack
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Price-14% $14.99
Typical:$17.39
$20.99$18.99-5% $26.99
List:$28.34
$28.99$27.99
Delivery
Get it as soon as Tuesday, Apr 2
Get it as soon as Tuesday, Apr 2
Get it as soon as Tuesday, Apr 2
Get it as soon as Tuesday, Apr 2
Get it as soon as Tuesday, Apr 2
Get it as soon as Tuesday, Apr 2
Customer Ratings
Easy to read
4.5
4.7
4.7
4.6
4.6
4.7
Easy to install
4.5
4.6
4.6
4.6
4.6
4.8
Accuracy
4.4
4.2
4.2
4.6
4.4
Value for money
4.3
4.2
4.2
4.3
5.0
Easy to use
4.2
4.7
4.8
Sold By
Amazon.com
Ecoey-direct
Ecoey-direct
SITERWELL
X-Sense US
Siterlink
power source
Battery Powered
Battery Powered
Battery Powered
Battery Powered
Battery Powered
Battery Powered
sensor type
Electrochemical
Electrochemical
Electrochemical
Electrochemical
Electrochemical
Electrochemical
style
Battery Powered
modern
Protection
Standard Model
Digital
alarm
Audible
Audible
Audible
Audible
Audible
Audible

Important information

Bulb Voltage

120 volts

Customer reviews

4.7 out of 5 stars
4.7 out of 5
19,143 global ratings

Customers say

Customers like the ease of installation, performance, value, and weight of the gas smoke fire alarm. For example, they mention it's easy to mount, works great, and is good value for money. Some appreciate the compact size and weight. That said, opinions are mixed on quality and battery life.

AI-generated from the text of customer reviews

545 customers mention479 positive66 negative

Customers like the performance of the gas smoke fire alarm. They say it works great, is easy to set up and install, and has a correct test function. Some mention that it's effective while being the simplest, and is a good brand.

"Greta carbon monoxide detector. Easy to set up and install. Test function works correctly. Definitely gives me peace of mind for the home." Read more

"Good brand and quality and price was good ! Good protection for the house." Read more

"I purchased two packs of the pack of 2. So far so good!? Tested fine. Hope it actually works, which is why I went with a name brand...." Read more

"They were easy to install and worked upon arrival; can't ask for much more than that. Please note these are battery operated, not plug-ins." Read more

528 customers mention469 positive59 negative

Customers like the ease of installation of the gas smoke fire alarm. They say the instructions are clear and easy to follow. They also mention that the template for installation is included.

"Greta carbon monoxide detector. Easy to set up and install. Test function works correctly. Definitely gives me peace of mind for the home." Read more

"Easy to install" Read more

"This monitor is easy to use and accurate. The battery feature vs plug in makes it easier to place higher up which is better...." Read more

"They were easy to install and worked upon arrival; can't ask for much more than that. Please note these are battery operated, not plug-ins." Read more

428 customers mention385 positive43 negative

Customers like the value of the gas smoke fire alarm. They mention it's a good buy and works great in their rentals.

"Good brand and quality and price was good ! Good protection for the house." Read more

"Trust the brand name and quality. The price was excellent" Read more

"I feel much safer in my home with these products. Worth the money." Read more

"Very well made, easy to install andat a reasonable price and delivered on time." Read more

110 customers mention93 positive17 negative

Customers like the weight of the gas smoke fire alarm. For example, they mention it's compact, easy to mount, and a great space saver. Some say it'll fit over existing screws and is light weight. That said, some say it works well and is great for travel.

"...It is small and light weight enough that it should be the thing to pack (take out battery, store separately until in room)...." Read more

"...I chose because of the brand name & its UL listed too and its small enough & dont take up much space with our packing." Read more

"Lightweight and small. Bought to take with me while traveling as I don’t trust all hotels when it comes to carbon monoxide leaks." Read more

"Great space saver and your brush will dry faster" Read more

349 customers mention198 positive151 negative

Customers are mixed about the quality of the gas smoke fire alarm. Some mention it's well made, and reassuring to have a reliable device that alerts them to potential carbon monoxide presence. However, others say that it started beeping and at first they thought it was the batteries.

"...Test function works correctly. Definitely gives me peace of mind for the home." Read more

"When I opened the package and tried to test my alarm, there was no light & no response...." Read more

"Good brand and quality and price was good ! Good protection for the house." Read more

"...the UL timelines, and even if there's an unsafe CO level, the device might not alarm if I turn my car off a half hour early...." Read more

258 customers mention102 positive156 negative

Customers are mixed about the battery life of the gas smoke fire alarm. Some mention that it comes with batteries, while others say that the battery included died within 2 weeks of installation.

"...Turns out the battery it came with was dead." Read more

"...The C0400 carbon monoxide detector comes with a 9 volt battery...." Read more

"...there's no way for you to access that info, and the alarm is unreliable for intermittent leaks...." Read more

"...Please note these are battery operated, not plug-ins." Read more

Batteries Weren't Dead - Testing Instructions Weren't Clear Enough
4 Stars
Batteries Weren't Dead - Testing Instructions Weren't Clear Enough
When I opened the package and tried to test my alarm, there was no light & no response. I thought the batteries were dead so I bought new ones, which did the same thing.It tuns out that testing requires holding the Test button, not tapping it. The light flashes once a minute, so 99% of the time, the unit appears to be dead.Once I knew to hold the button, I was able to confirm they appear to be operating properly after all. Better labelling would have saved me the cost of replacement batteries.
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Top reviews from the United States

Reviewed in the United States on March 24, 2024
Size: 2 Count (Pack of 1)Pattern Name: DetectorVerified Purchase
Reviewed in the United States on February 5, 2024
Size: Pack of 3Pattern Name: DetectorVerified Purchase
Reviewed in the United States on March 11, 2024
Size: 2 Count (Pack of 1)Pattern Name: DetectorVerified Purchase
One person found this helpful
Report
Reviewed in the United States on March 11, 2024
Size: 2 Count (Pack of 1)Pattern Name: DetectorVerified Purchase
Customer image
4.0 out of 5 stars Batteries Weren't Dead - Testing Instructions Weren't Clear Enough
Reviewed in the United States on March 11, 2024
When I opened the package and tried to test my alarm, there was no light & no response. I thought the batteries were dead so I bought new ones, which did the same thing.

It tuns out that testing requires holding the Test button, not tapping it. The light flashes once a minute, so 99% of the time, the unit appears to be dead.

Once I knew to hold the button, I was able to confirm they appear to be operating properly after all. Better labelling would have saved me the cost of replacement batteries.
Images in this review
Customer image
Customer image
5 people found this helpful
Report
Reviewed in the United States on January 13, 2023
Size: 2 Count (Pack of 1)Pattern Name: DetectorVerified Purchase
52 people found this helpful
Report
Reviewed in the United States on March 22, 2024
Size: Pack of 1Pattern Name: DetectorVerified Purchase
Reviewed in the United States on January 31, 2024
Size: 2 Count (Pack of 1)Pattern Name: DetectorVerified Purchase
Reviewed in the United States on March 6, 2024
Size: Pack of 1Pattern Name: DetectorVerified Purchase

Top reviews from other countries

Monica Ileana Silva Davila
5.0 out of 5 stars Bien!
Reviewed in Mexico on March 18, 2024
Size: 2 Count (Pack of 1)Pattern Name: DetectorVerified Purchase
Amazon Customer
5.0 out of 5 stars Excellent and easy to install
Reviewed in Canada on December 17, 2016
Size: Pack of 1Pattern Name: DetectorVerified Purchase
Corey S
5.0 out of 5 stars Simple
Reviewed in Canada on August 18, 2018
Size: Pack of 1Pattern Name: DetectorVerified Purchase
JIW
4.0 out of 5 stars Great
Reviewed in Canada on June 19, 2019
Size: Pack of 1Pattern Name: DetectorVerified Purchase
roger skinner
5.0 out of 5 stars Safety
Reviewed in Canada on March 18, 2019
Size: Pack of 1Pattern Name: DetectorVerified Purchase