About this product

Product Information

Carbon monoxide is deadly, yet you can't see or smell it. With this First Alert CO400 Battery Powered Carbon Monoxide Alarm, you'll stay safe even when the electrical power is off. The electrochemical sensor inside this device accurately detects when carbon monoxide increases to dangerous levels. It also has a mute button for those times when carbon monoxide is released from a cooking mishap. It easily mounts on walls so that you can keep multiple areas of your residence safe.

Product Identifiers

BrandFirst Alert

MPNCO400

GTIN0617407371796, 0029054009166, 0736569087649, 0490920802714, 0715007535003, 0736569083399, 3245426892014, 0777786600228, 0029054000699, 0029054000743, 0029054856067

UPC0617407371796, 0029054009166, 0736569087649, 0490920802714, 0715007535003, 0736569083399, 3245426892014, 0777786600228, 0029054000699, 0029054000743, 0029054856067

ModelCO400

eBay Product ID (ePID)2254447842

Product Key Features

Power SourceBattery

ColorWhite

Item Depth3.4in.

FeaturesPortable

TypeCarbon Monoxide Detector

Smart Home ProtocolCombination

Dimensions

Item Width1.5in.

Depth3.4in.

Item Weight0.7lbs.

Additional Product Features

Battery IncludedYes

Ratings and reviews

Learn more

4.8

174 product ratings

150 users rated this 5 out of 5 stars
14 users rated this 4 out of 5 stars
5 users rated this 3 out of 5 stars
1 users rated this 2 out of 5 stars
4 users rated this 1 out of 5 stars

Would recommend

Good value

Good quality

Most relevant reviews

See all 120 reviews

by bur_877557
12 Jan, 2022Top favourable review
Very easy to Install, All Hardware included.
Arrived very quickly and well packaged. Client was pleased to now have a protective device to notify them of carbon monoxide build up within their basement and living area. Each package included the necessary mounting hardware and a template to drill the correct spacing for the screws.
Verified purchase: YesCondition: New
by artremaus
12 Dec, 2015Top critical review
Caution-Limited Shelf Life-Check the date.
This is 2015. The detectors purchased on eBay had 2007 dates on them. I contacted First Alert and they said to throw them away. The chemical compound that reacts to CO wears out regardless of whether the units are powered up so the shelf life is limited. I bought new ones at Target ($20 ea.) and they were only 2 months old. Too bad you can't see the date until you open the package but I opened one up as soon as I bought it and was prepared to return it if it was old.
Verified purchase: YesCondition: Pre-owned
by plym_953
24 Sep, 2019
Carbon monoxide detector
Detector was easy to install works great the price comparable with others if not better highly recommend to others
Verified purchase: YesCondition: New
by pizzaboyy
12 Jan, 2021
Does its job, uses 9-volt
Needed to replace an end-of-life unit that used AA batteries. Thought this one would use the same, but it uses 9-volt. The mounting bracket distance was changed, so I needed to drill a new hole for it. Does its job, I hope!
Verified purchase: YesCondition: New
by rola_rohd
24 Feb, 2020
Great little inexpensive alarm.
I like that the alarm has a silence feature that allows you to silence it for a few minutes while attending to the issue if the alarm sounds.,Gives you time to get the device down and replace the batteries. It also has a light that blinks hourly to show the alarm is in working order. Its also very light weight and small.
Verified purchase: YesCondition: New
by thuyge2807
07 Apr, 2016
Life Saver
I bought this alarm to replace one that had lasted for 8 years. It's an exact replacement because the earlier one was a great product, and I'm very pleased with First Alert products. If you have a gas furnace, stove, or hot water heater, I would recommend having one of these installed in your home.
Verified purchase: YesCondition: Pre-owned
by sunnyskies43
09 Oct, 2019
great product and low cost
had one before, lasted seven years. First alert said it would last seven years, they were correct. good use no problems.
Verified purchase: YesCondition: New
by andrewmminer
27 Jan, 2021
name brand, good proce
it is a replacement and works fine but I was disappointed that it was more than several years old, it is name brand, seems to be just fine, we'll see if it lasts as long as it should being so old.
Verified purchase: YesCondition: New
by steve070909
25 Jan, 2017
Good size, reasonably priced, does the trick.
Only caveat I would say is that if you had an older model, for some reason, I believe they changed the batteries from AA to 9 volt and the width of the two hanging screws on the back widened so you will have to redrill another hole.
Verified purchase: YesCondition: New
by chrysa71
12 Feb, 2018
Feel safe now!
This is a great battery operated (batteries included) carbon monoxide detector. It’s nice and loud too! It’s smaller so you can put it just about anywhere. I have a 5 level townhome and I put it in the 4th floor hallway - on a little table. Peace of mind. :-)
Verified purchase: YesCondition: New