If you own a carbon monoxide detector, you may notice a certain expiration date written on your device. This first started to make me curious, as I wondered whether carbon monoxide detectors go bad. Why do they expire?
What exactly is going to happen if the CO detector expires without being replaced? Does it stop detecting carbon monoxide after its expiration date? I will answer the question “why do carbon monoxide detectors expire?” in detail.

What is a Carbon Monoxide Detector?
Carbon monoxide detectors are devices that detect carbon monoxide – the invisible, odorless gas that is one of the leading causes of poisoning death in North America.
Carbon monoxide detectors use an electrochemical cell (also called a gas sensor) to detect carbon monoxide concentrations in the air. They sound an alarm when they detect unsafe levels of carbon monoxide.
Here are some of the most effective carbon monoxide detectors.
When you get a CO detector, the manufacturer sets an expiration date for the device. This is usually between 5 and 7 years from when you first buy it. The expiration date on your carbon monoxide detector is not a “use by” or “best before” expiry date.
In other words, it is not the date on which you have to throw out your CO detector. The expiration date on a CO detector simply means that after this time the carbon monoxide detector will no longer detect carbon monoxide.
Why Do Carbon Monoxide Detectors Expire?
Manufacturers put an expiration date on every single one of their carbon monoxide detectors, but they never explain why. The reason is that the electrochemical cells used in carbon monoxide detectors have a limited lifespan – they can only be used for 5 to 7 years.
The electrolyte liquid inside the gas sensor evaporates over time, which changes the internal resistance of the cell. This means that after about 5-7 years the cell gradually becomes less sensitive to carbon monoxide, and this can affect how well your carbon monoxide detector detects CO.
How Do You Know When It’s Time to Change Your Carbon Monoxide Detector?
The expiration date on a CO detector is there to ensure that you always have a working CO detector in your home.
Manufacturers don’t want to inconvenience people or cause them unnecessary expenses, so they recommend that you change your CO detector at the same time as you change your smoke detectors.
You can also use a CO detector to detect carbon monoxide leaks in other appliances such as gas ranges and water heaters. If you replace these appliances within 5-7 years of each other, you can replace the CO detector at the same time.
How Long Does a Carbon Monoxide Detector Last?
Even if your carbon monoxide detectors never expire, it is not a good idea to use them forever. The working life of a CO detector can vary depending on its quality and manufacturing type.
If you buy cheap, low-quality detectors for your home, you may need to replace them more frequently. I recommend that you replace carbon monoxide detectors every 5 years.
Read more on home security cameras to use with CO detectors
5 Best Carbon Monoxide Detector for Home
1. X-sense CD07 Carbon Monoxide Detector Alarm

Built to withstand the wrath of Mother Nature, this powerful CO detector quickly and accurately detects threats in the surrounding air. With an advanced electrochemical sensor and intelligent chipset, you’ll never go unawares once you install this sleek carbon monoxide alarm inside your home or office!
Soothing LED lights will help keep your home safe while a loud 85 dB alarm alerts all by its lonesome if danger is headed your way. As a secondary protection measure, the CD07 gives off a rapid flashing red light so even if it’s buried under furniture or tucked away from sight, it can still get to you in time for some quick escape from whatever doom may be following on its heels.
It features a 10-year lithium battery for guaranteed uninterrupted service. Additionally, the CO detector comes with a fire retardant housing.
“We all know the dangers of carbon monoxide – this is why we’ve designed an alarm with a 10-year battery for worry-free protection. The clear, large LCD continuously monitors CO levels in real-time while also providing more information on the peak measured concentration. A remote controller can be used to test an area and determine whether or not there were high levels of CO present.”
“With easy installation and after-sales service, you can rest assured that your health will always be taken care of.”
2. Kidde Carbon Monoxide Detector, Plug-In with Battery Backup

Sleek and modern, the Kidde Carbon Monoxide Detector features a lithium battery that backs up your home in case of a power outage. Keep it plugged into a standard wall outlet to keep tabs on CO levels – lasts about 10 years.
Just plug this sleek carbon monoxide detector into an electrical socket near ground level, if you have one available, to track CO readings as they rise! It’s so simple to use- just slide the side switch from ‘LED’ to ‘CO.’
In addition, its compact design will clean your cluttered plugs by giving those empty spaces company- all while warning you of toxic gas. You can even place one near each level of your home (and bedroom!) for family safety.
3. First Alert SCO5CN Combination Smoke and Carbon Monoxide Detector

The First Alert SCO5CN Combination Smoke and Carbon Monoxide Detector is the perfect product for all-over protection in your home. It can be installed quickly and easily and senses smoke and CO even during 24-hour use.
The low battery signal will let you know when to change the pre-installed battery that comes with the unit, but if it starts making a high-pitched alert noise that may mean that it’s time to replace it altogether.
4. Kidde Smoke & Carbon Monoxide Detector, Battery Powered, Combination Smoke & CO Alarm

This alarm is a little different from a normal one. It has lots of features that make it special. First, the ionization sensor technology means it detects invisible fire particles too—so there’s no need to worry about something you can’t see!
Second, when the power goes out and your regular smoke detector system malfunctions this Kidde Smoke & Carbon Monoxide Detector operates on 2-AA batteries so not to worry!
And lastly, since its 10-year limited warranty will let you sleep sounder without any concerns you’ll be covered in case anything ever did happen to go wrong with your Kidde Smoke and Carbon Monoxide detector.
5. Furado Carbon Monoxide Detector 3 Pack, CO Detector Alarm Sensor

Furado Carbon Monoxide Detector 3 Pack, CO Detector Alarm Sensor – Build-in Carbon Monoxide Detector Chip and the electrochemical sensor, Enough to detect odorless invisible and deadly carbon monoxide in the air.
3 digits LCD displayer on the LCD to indicate if the unit is malfunctioning. ‘Lb’ on LCS to indicate it low battery and need replacement. ‘999ppm’ on the LCD to indicate CO level over 999ppm
And Loud 85 decibel alarm with LED Flash While in the alert mode for life-saving safety. When a dangerous level of carbon monoxide is detected, a loud alarm pattern will sound–a Loud 85-decibel alarm with LED flashing red light.
Why Do Carbon Monoxide Detectors Expire? Conclusion
Carbon monoxide detectors expire for several reasons: the material used in their creation, their manufacturer, and when they were manufactured.
Every device has at least one small part that will inevitably fail, no matter how well it is made. This is why many devices such as smoke alarms and carbon monoxide detectors come equipped with expiration dates.
Manufacturers make devices with parts that will last as long as possible without breaking, but those parts can still wear down and fail. Even the least expensive device can become priceless under the right circumstances, and expiration dates play a role in ensuring you get your money’s worth from a purchase.
Of course, an expired carbon monoxide detector doesn’t stop working completely, it just stops functioning the way it should.
This means that you will no longer be aware of levels around you that could prove dangerous. This is why it’s important to check your device at least once every month and replace old detectors as needed.
If you’re not sure how old your carbon monoxide detector is, compare it with the ones in this guide. Any of our picks is at least six years old and most are 10 years old, so if you’re not sure what to look for, that will give you a good idea.