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

4.6 4.6 out of 5 stars | 20,672 ratings

Price: 16.49

Last update: 12-28-2024


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)

Product information

Technical Details


Top reviews from the United States

Amazon customer
5.0 out of 5 stars Great product
Reviewed in the United States on July 26, 2024
Easy to install , good quality, durability.
S. Nelson
5.0 out of 5 stars Life Saver
Reviewed in the United States on July 28, 2024
This product probably saved our lives. We have one gas powered appliance, a propane fireplace, which hasn’t been on in months. The detector alerted us out of a sound sleep early one Sunday morning. Not the dead battery chirp, but four alarm beeps and a pause, over and over. Called 911. Fire department arrived with their hand held detector which alerted several times to confirm the presence of CO. We disconnected the tank(which was off) opened all the windows, turned on all the fans and left. Worth the price a thousand times over.
Steve-o-matic
5.0 out of 5 stars Review: First Alert CO400 Carbon Monoxide (CO) Detector, Battery Operated Alarm, 1-Pack
Reviewed in the United States on August 2, 2024
I purchased this to replace an aged unit. I have had several of these over the years and never had any issues. The batteries last well over a year. Manufacturer states the unit has a life span of 5 years. I have found this to be accurate. The unit will let you know when it reaches that point. Be sure to read the instructions for proper installation, testing, and maintenance.
S. F.
4.0 out of 5 stars Good product
Reviewed in the United States on June 21, 2024
Easy peasy - once you figure out the battery door! (One star off for THAT!) Man, I thought I was going to snap that thing right off! Don’t think they want the battery coming out because that little door is tight! “Push and pull” isn’t going to cut it for instructions, might be better to provide more details and better graphics/pictures! Will wait and see about functionality and battery life!
LMG
5.0 out of 5 stars Very reliable carbon monoxide detector
Reviewed in the United States on June 12, 2024
This detector is small, compact, easy to test, and quite reliable. Our previous identical one lasted many years. The only difficult aspect here is the effort it takes to open the battery compartment. Still, all in all, a fine purchase.
Precise Disarray
5.0 out of 5 stars for home, for travel, for car (add to winter car bag in case stuck in blizzard). 9 volt included
Reviewed in the United States on January 13, 2023
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. This is not the place to skimp.

The C0400 carbon monoxide detector comes with a 9 volt battery. I knew I needed to replace my existing detector (they dont last forever, and need to be replaced ever so often) and I did not want the plug in style. I wanted battery operated so I could place it wherever I wanted and not be limited to available outlets. I also bought a second pack as a gift. I prefer giving practical, functional gifts, especially stuff that people tend to not want to buy, such as smoke alarms, fire extinguishers, carbon monoxide detectors.

If you travel, consider a battery operated detector such as this. Dont trust that a hotel room has you covered, or someone else's house. It is small and light weight enough that it should be the thing to pack (take out battery, store separately until in room).

I will likely buy an additional pack. Right now I have one on the first floor, and one outside my second floor bedroom door. I think having one in the basement and another in actual bedroom or elsewhere (spread out) would be better. Watch for sales, but if need be just buy them at any cost so you have them.

I am even thinking about adding one to my winter car kit. If ever stuck in a blizzard and had to stay in my car for any length of time, having a detector will help as CO2 levels can quickly rise if running car (or if a few people are simply breathing without the window open a crack) to keep warm. Tail pipes can easily clog especially if windy. So yeh, simple thing to stay safe and alive
Janet Hodson
5.0 out of 5 stars It works!
Reviewed in the United States on May 27, 2024
My first alert let me know that it was dying and I needed to replace the whole unit. So I purchased another from Amazon and I can say that this brand works very well. It did its job! Small enough to put in a spot where it doesn't stand out. The decibels it puts out is loud but it will save a life!
Tatt2edtears06
5.0 out of 5 stars Good replacement
Reviewed in the United States on July 11, 2020
When I purchased my home back in 2014 we bought the same brand (First Alert) carbon monoxide detector that looked just like this one. Recently it started beeping and at first I thought it was the batteries but soon found out that the alarm was actually telling me it was out of date and needed to be replaced. I did not realize they only lasted so long but they do have an expiration date! So... I got online and was trying to find a replacement. I did not find the exact same one (mine took AA batteries) however this one looked JUST like the one I previously had so I purchased it. I made sure this one was battery operated as I do not want to have to hardwire one. When I received it I was happy to see that it actually came with the 9V battery it needs to work. It was very easy to take out of the package and even had a perforated aread you just pull open. You open up the battery housing and the battery was easy to install. This comes with screws for installation as well but I just used the ones I had existing from my last detector. However because this one was slightly different I did have to adjust one of the nails in my wall to make them an even 3 1/2 inches apart. It hung up nicely within 5 minutes of my opening the package it was installed and ready to go. Will definitely be purchasing the same brand next time!
Customer image
Tatt2edtears06
5.0 out of 5 stars Good replacement
Reviewed in the United States on July 11, 2020
When I purchased my home back in 2014 we bought the same brand (First Alert) carbon monoxide detector that looked just like this one. Recently it started beeping and at first I thought it was the batteries but soon found out that the alarm was actually telling me it was out of date and needed to be replaced. I did not realize they only lasted so long but they do have an expiration date! So... I got online and was trying to find a replacement. I did not find the exact same one (mine took AA batteries) however this one looked JUST like the one I previously had so I purchased it. I made sure this one was battery operated as I do not want to have to hardwire one. When I received it I was happy to see that it actually came with the 9V battery it needs to work. It was very easy to take out of the package and even had a perforated aread you just pull open. You open up the battery housing and the battery was easy to install. This comes with screws for installation as well but I just used the ones I had existing from my last detector. However because this one was slightly different I did have to adjust one of the nails in my wall to make them an even 3 1/2 inches apart. It hung up nicely within 5 minutes of my opening the package it was installed and ready to go. Will definitely be purchasing the same brand next time!
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