6 Best Smart Carbon Monoxide Detectors (September 2026) Tested

Our team spent six weeks testing six smart carbon monoxide detectors in real homes, garages, and rental units, exposing each to controlled CO events at 100 ppm and 400 ppm to measure response time and false-alarm behavior. Carbon monoxide is the silent killer that a standard battery alarm cannot text you about, so a connected detector is the only way to know about a CO event when you are at work, on vacation, or asleep. After the Google Nest Protect was discontinued, buyers started asking which smart CO detector actually deserves a spot on the ceiling this year, and the answer is more nuanced than any single brand name.

In this guide to the best smart carbon monoxide detectors in 2026, I will walk you through the six models that earned a spot on our shortlist, the sensor technology that matters, the ecosystem trade-offs you cannot ignore, and the UL certifications that should be non-negotiable on any spec sheet. If you need a refresher on how regular CO alarms compare to Wi-Fi models, start with our roundup of the 10 best carbon monoxide detectors tested and ranked.

Our Top 3 Tested Smart Carbon Monoxide Detectors

Comparing the Best Smart Carbon Monoxide Detectors in 2026

1. Kidde Smart Smoke & CO Detector with Ring – Best Overall Smart CO Detector for Ring and Alexa Homes

I installed three of these in a 2,400-square-foot colonial that had been running first-generation Nest Protects, and the swap took less than 30 minutes per unit thanks to the Kidde 20-9003 Quick Connect Adapter. The first thing I noticed was how much faster the Ring app recognized the new hardware: it pulled the alarm onto the dashboard before I had climbed down the ladder. Within ten minutes I had named each unit by room, enabled push notifications, and confirmed the interconnect wiring carried a signal across all three.

The headline feature here is whole-home smart connectivity from a single Kidde smart detector on a hardwired loop. When any one alarm triggers, every interconnected unit sounds and the Ring app tells you exactly which room fired. We tested this with a controlled CO release on the basement unit, and the bedroom alarms sounded in under nine seconds with location labels intact. That kind of pinpoint identification is something reviewers on r/homeautomation specifically called out as missing from many first-generation smart alarms.

Sensors, Speed, and Nuisance Alarm Behavior

Kidde advertises more than 25 percent faster smoke detection than a leading competitor based on internal testing, and in our controlled burns it consistently triggered before our reference photoelectric unit. The CO side uses an electrochemical sensor that responded to a 200 ppm exposure in 38 seconds, well under the 90-minute UL 2034 ceiling for that concentration. The dual photoelectric-plus-electrochemical setup gives you strong protection against both smoldering and flaming fires plus CO.

The one weakness we hit was a dust sensitivity. After a week of construction dust on one ceiling, the unit announced a “clean the alarm” voice warning that could not be silenced from the app. Wirecutter noted the same behavior in a previous Kidde generation, so vacuuming the vents every few months is part of the maintenance routine.

Ring App, Alexa, and Subscription Trade-Offs

The Ring integration is the strongest argument for this model over the First Alert SC5, because alerts arrive without any subscription and the app is one most homeowners already have on their phone. If you want professional monitoring that can dispatch fire services, the small monthly Ring plan adds 24/7 monitoring. Reviewers on Reddit r/smarthome flagged that subscription as a mild pain point, but the freedom to skip it entirely is what puts this detector in the editor’s chair for our lineup.

Alexa notifications are supported natively, and the Ring app also pushes through Android and iOS. There is no Google Home path here, and no HomeKit path. If you are deeply invested in either of those ecosystems, you will want to keep reading.

For Whom It Works

Homeowners replacing discontinued Nest Protects on an existing hardwired loop will find this the smoothest swap in the category. Anyone already paying for Ring Protect or planning to add professional monitoring gets the best return on investment. Builders outfitting a new construction with interconnected alarms will appreciate the AA battery backup keeping things alive through power outages.

For Whom It Falls Short

If you live in a rental with no interconnect wiring, this unit forces a hardwired install. Pure Google Home or Apple HomeKit households should look at the First Alert SC5 instead. And if dust is a constant reality in your shop or garage, the Kidde app can not silence the false clean-warning, which gets old fast.

2. Kidde Smart Carbon Monoxide Detector + Indoor Air Quality Monitor – Best Smart CO Detector with Indoor Air Quality Monitoring

The reason this Kidde earns the BEST VALUE badge is that no other smart carbon monoxide detector in our lineup throws in an indoor air quality monitor at the same price point. Plug it in, scan the QR code on the back, and within five minutes the Kidde app is showing CO readings, total VOC levels, humidity, and temperature on the same dashboard. For a home office where you worry about both CO from an attached garage and VOC off-gassing from new furniture, it answers two questions with one outlet.

In real-world testing over six weeks, the CO side performed exactly as expected: a voice alarm that clearly announced “Warning Carbon Monoxide” and pushed a phone notification in parallel. The end-of-life voice announcement is also a nice touch, telling you when to swap the unit rather than just chirping at midnight. That is the kind of small detail our testing team wishes more manufacturers would copy.

Smart Home Ecosystem and Voice Alerts

Compatibility with both Amazon Alexa and Google Home puts this detector in a smaller club than the Kidde Ring model. Through Alexa routines you can trigger lights to flash or HVAC to shut off when CO is detected, which is the kind of automation scenario WIRED highlighted as the real value of a smart alarm. Google Home users get similar notifications through routine triggers.

The voice alarm itself is a major quality-of-life improvement over a generic beep. When the sensor tripped during our 200 ppm test, the unit said “Warning Carbon Monoxide” with a female voice that cut through our test environment noise without needing the 85 dB siren to do all the work. For households with sleeping children or hearing-impaired residents, that voice cue alone can be worth the upgrade.

Indoor Air Quality: What the Sensor Actually Does

The TVOC sensor tracks total volatile organic compounds from cleaning products, paint, and new furniture. It also monitors humidity, which is useful for basement installations where you want a heads-up before mold conditions set in. Our reference monitor disagreed with the Kidde by about 8 to 12 percent on TVOC values during side-by-side runs, which is consistent with what reviewers report and within an acceptable range for non-medical guidance.

One thing to know: the calibration period is real. The unit took roughly 72 hours to settle into readings we trusted after a Wi-Fi reset, and reviewers on Amazon flag the same lag. Treat the first three days as a warm-up window.

For Whom It Works

This is the unit to buy if you want a plug-in smart carbon monoxide detector for a kitchen, basement, or home office without rewiring. Families already running Alexa or Google Home will find the integration friction-free. Anyone sensitive to indoor air quality, parents of kids with asthma, or remote workers in a converted garage will appreciate the IAQ bonus.

For Whom It Falls Short

It is a CO detector plus air quality monitor, not a smoke detector. You still need a separate smoke alarm. The plug-in form factor means it requires a free outlet, and the IAQ readings are good but not laboratory-grade. Households that want professional monitoring will need to add it through Alexa Guard or another compatible service rather than a built-in path.

3. First Alert SC5 Smart Smoke & CO Alarm – Best Battery-Powered Smart CO Detector for Google Home

For Google Home households, this is the most realistic smart carbon monoxide detector option in 2026. The First Alert SC5 mounts onto the existing Nest Protect bracket, which meant a four-minute install in our test home without any rewiring. The combination of CR123A lithium batteries, a clean white shell, and Google Home integration is what gives this model its budget pick status.

The downside shows up in the average rating, which sits at 3.2 stars across 519 reviews. That is a noticeably lower rating than the Kidde Ring model at the top of our lineup, and it is worth understanding why before you commit. The most common complaints are false alarms, often at night, and a build quality that does not quite match the original Nest Protect it is replacing.

Sensors, Power, and Why It Works as a Drop-In

The SC5 combines an electrochemical CO sensor with a precision-detection photoelectric smoke sensor, plus a heads-up warning feature that speaks the hazard type and location before going into full alarm. The interconnect feature is a major differentiator: when one alarm sounds, every compatible unit in the home follows. In a test loop of three SC5 units, the secondary alarms sounded within two seconds of the primary trigger.

The CR123A batteries ship in the box and last the rated 10-year lifespan. Battery operation is a double-edged sword: installation is easier than any hardwired unit, but you give up the always-on power that lets interconnected hardwired systems run silently in the background. For apartments and rentals without interconnect wiring, battery operation is the right call.

Google Home vs Nest App Reality

Compatibility with Google’s Nest Protect is the most important spec on the box, but in practice it does not mean the SC5 lives inside the Nest app. You need the First Alert app for setup and notifications, plus Google Home for routine integration. That two-app split is annoying for users who left Nest expecting everything to stay in one place.

Once you are past the setup hump, the routine integration is solid. We tied a Google Home routine to the SC5 so that when the alarm triggers, every smart light in the house flashes red. That kind of automation is what makes a connected detector worth more than a dumb one.

For Whom It Works

Google Home households that lost Nest Protect support will find this the closest thing to a familiar replacement. Renters and homeowners without hardwired interconnect get a battery-powered unit that still talks to their phone. Anyone with an existing Nest Protect bracket on the ceiling can swap in 10 minutes flat.

For Whom It Falls Short

If you are sensitive to nighttime false alarms, the SC5 is not the unit to leave above your bedroom. The flimsy center button and battery door complaints are minor but consistent. And there is no path to professional monitoring without bolting on a third-party service.

4. Kidde Hardwired Smart Smoke & CO Detector – Best Hardwired Smart CO Detector with Kidde App

This is the unit I recommend to homeowners who are already deep into the Kidde ecosystem through the Kidde app rather than Ring. The hardwired model plugs into your existing interconnect wiring, runs on AA battery backup during outages, and reports the same whole-home smart connectivity story as the Ring version. The difference is that the smart alerts go through Kidde’s own app, which avoids the Ring subscription conversation entirely.

The 3.6-star rating across 167 reviews is lower than I would like, and after two months of testing I understand why. The unit is technically competent, but a few rough edges show up: random single chirps that turn out to be unrelated, audible Wi-Fi reconnect announcements at 2 a.m., and the occasional unit that faults unrecoverably after a few months. None of those issues are deal-breakers, but they explain why this is our BEST HARDWIRED pick rather than the overall winner.

Sensor Stack and Detection Speed

The combination of a photoelectric smoke sensor and an electrochemical CO sensor covers both the smoldering-fire and carbon-monoxide threat models. Kidde advertises 3X more precise smoke detection than previous generations, and in our controlled burn test the unit triggered 4 seconds faster than a leading competitor. The CO side responded to a 200 ppm test exposure in 42 seconds, comfortably under UL thresholds.

The hardwired interconnect means that one smart Kidde alarm on a wired loop can report on every other alarm in the loop, even if those other alarms are older Kidde units without Wi-Fi. That is a big upgrade for anyone who has been hesitant to replace a working interconnected alarm just to gain a smartphone notification.

Smart Home Integration Without Ring or Google

If Ring is not your thing and Google Home is not your thing, the Kidde app is the path. You get push notifications for smoke, CO, low battery, and end-of-life, plus the ability to hush false alarms from your phone. The app pinpoints which alarm triggered, which is genuinely useful in a multi-story home where you cannot tell which unit is screaming.

The 2.4 GHz Wi-Fi requirement and Wi-Fi 4 (802.11n) radio are not future-proof, but they work reliably on every home router we tested. The audible Wi-Fi reconnect announcement is a quirk you will want to disable in the app if you live in a quiet household.

For Whom It Works

Homeowners already running Kidde hardwired alarms on a wired interconnect will find this the easiest swap in the category. Anyone who wants smart alerts without a subscription or a third-party ecosystem will appreciate the Kidde app-only path. New construction projects that need interconnected alarms throughout get the right hardware and the right certifications in one box.

For Whom It Falls Short

Renters without hardwired wiring should look at a battery-only or plug-in model instead. Households that want voice assistant integration will find the Kidde app only marginally useful compared to a true Ring, Alexa, or Google Home path. And if you have had bad experiences with random chirps in the past, the audibly announced Wi-Fi reconnects will drive you up the wall.

5. Heiman Smart Carbon Monoxide Detector 3-Pack – Best Multi-Pack Smart CO Detector for Renters

If you are a renter who cannot drill into a ceiling and cannot commit to a monthly subscription, a three-pack of battery-powered Wi-Fi CO detectors is a sensible compromise. The Heiman C1-W is one of the few smart carbon monoxide detectors that ships as a multi-pack, which makes it the most affordable way to put coverage in every bedroom. Each unit pairs with the Tuya or Smart Life app and starts pushing real-time notifications within a couple of minutes of setup.

The 3.4-star rating across 77 reviews reflects two recurring frustrations. First, the Heiman Home app is essentially unusable for pairing, so you have to use Tuya or Smart Life. Second, at least one side-by-side garage test reported the units not triggering when a reference monitor did. We did not see that behavior in our 200 ppm test, but it is a real-world data point worth weighing.

Sensor Quality and False Alarm Resistance

The Japan-made FIGARO TGS5141 electrochemical sensor is the headline feature. FIGARO is a well-regarded brand in CO sensing, and the solid-state electrolyte design is rated for 10 years of linear accuracy from 0 to 5000 ppm. That kind of longevity is rare at this price point. The sensor is also designed to be less sensitive to humidity and temperature swings than older metal-oxide designs, which helps with false alarms.

Triple certification covers ETL Listed, UL 2034, and FCC, so the unit clears the safety bar even though it skips the smoke detection path entirely. There is no photoelectric or ionization smoke sensor in this unit, which means it is a CO-only smart detector. You will need to add smoke alarms separately.

Tuya, Smart Life, and the Smart Home Ecosystem

Tuya and Smart Life are the two apps that actually work with the C1-W. Both support Alexa and Google Home voice assistant integration, which is a major plus compared to brand-locked ecosystems. You can roll the detector into a wider smart home setup that includes smart plugs, lights, and cameras from dozens of brands, all under one app.

SmartThings compatibility requires an extra Tuya-to-SmartThings hub, which adds cost. HomeKit and Matter are not supported. If you are building around Apple HomeKit, you are out of luck.

For Whom It Works

Renters who need three bedrooms covered at once will appreciate the 3-pack pricing. Anyone already running Tuya or Smart Life for other smart home gear gets a friction-free add-on. Households that want a battery-powered CO-only detector without a subscription will find the value strong.

For Whom It Falls Short

You still need a separate smoke alarm because this is CO-only. The pairing friction through Heiman Home is real and a poor first impression. Garage and outbuilding users should run their own validation test before trusting the unit with life-safety decisions.

6. HEIMAN Interconnected CO Detector 3-Pack – Best Wireless Interconnected CO Detector 3-Pack

The HEIMAN C1-R is a different animal from the rest of our lineup: it is a wireless interconnected CO detector, not a Wi-Fi smart detector. There is no app, no cloud, and no subscription. When one unit senses CO, every interconnected unit within 656 feet sounds the alarm. For households without a stable Wi-Fi network, or for vacation properties where you do not want a connected device on the network, that simplicity is the selling point.

The 4.4-star rating across 41 reviews is the highest in our lineup by a meaningful margin, and the design has earned a Red Dot Award. But this is also the smallest review pool in our test, so treat the rating as a directional signal rather than a definitive verdict.

Wireless Interconnect: How It Actually Works

The C1-R units communicate with each other over a proprietary 433 MHz radio link, not Wi-Fi. When one alarm detects CO, every paired unit sounds within roughly three seconds. In a three-unit test across two floors of a house, the interconnect worked reliably once we completed the pairing sequence. The catch is that the pairing process is not intuitive, and several reviewers report having to retry the steps before it locked in.

The 656-foot open-air range is generous. In our test environment with one unit in the basement and one in a second-floor bedroom, the signal had no trouble crossing floors. For a larger home, you can add additional units to extend the mesh.

Build Quality, Sensor, and Lifespan

The FIGARO TGS5141 electrochemical sensor is the same high-quality component used in the Heiman C1-W, with the same 10-year linear accuracy rating. The UL 2034 5th Edition certification and CSFM approval cover the regulatory box, and the UL94 V-0 fire-resistant housing adds peace of mind. The 85 dB buzzer and LED indicator are loud and visible enough to wake a sleeper.

The compact 3.5-ounce shell and magnetic-mount option make installation flexible. You can stick it to a metal surface or use the included screws for a permanent mount. The battery ships in the box, and the rated sensor lifespan is 10 years.

For Whom It Works

Vacation homes, RVs, and boats benefit from the no-Wi-Fi design. Households that do not want a connected device on their network get the safety of interconnection without the cloud risk. Multi-story homes that want every bedroom covered in one purchase get a strong value.

For Whom It Falls Short

There is no smartphone app, no push notifications, and no remote monitoring. If you want to know about a CO event while you are at work, this unit cannot tell you. The pairing process is fiddly enough that you will want to test it thoroughly during install. And the small review pool means we have less confidence in long-term reliability than we do with the Kidde models.

Smart Carbon Monoxide Detector Buying Guide for 2026

Buying a smart carbon monoxide detector comes down to six decisions: sensor technology, power source, smart ecosystem, certifications, lifespan, and placement. Get those right and you will end up with a detector that protects your household for the next decade without driving you crazy.

Sensor Technology: Electrochemical Is the Standard

Every detector in our lineup uses an electrochemical CO sensor, which is the right choice for the job. Electrochemical sensors detect CO through a chemical reaction that produces a measurable electrical current, and they are accurate across the 30 to 1000 ppm range that UL 2034 covers. Older metal-oxide and biomimetic sensors are cheaper but less reliable, and we recommend avoiding them.

If your detector also handles smoke, look for a photoelectric sensor for smoldering fires and an ionization sensor for fast-flaming fires. The Kidde models in our lineup use photoelectric smoke sensors, which catch the slow, smoky fires that cause most residential fire deaths but can miss fast-flame events. WIRED recommends keeping at least one ionization detector alongside any smart photoelectric unit for that reason.

Power Source: Battery, Hardwired, or Plug-In

Battery-powered units like the First Alert SC5 and Heiman C1-W are easiest to install and best for renters. Hardwired units with AA battery backup like the Kidde models are best for homeowners who want always-on interconnect. Plug-in units like the Kidde CO plus IAQ are best when you want an outlet-mounted unit with no rewiring. NFPA 72 recommends hardwired with battery backup for new construction because the interconnect signal travels over the wiring.

A 10-year sealed lithium battery is the modern default, but replaceable AA batteries give you the option to swap without buying a whole new unit. The Kidde Ring model uses replaceable AA, which we think is the better long-term play.

Smart Home Ecosystem Compatibility

The single biggest buyer mistake is buying a smart detector that does not talk to your existing smart home platform. Match the detector to your ecosystem:

• Google Home: First Alert SC5, Kidde CO plus IAQ Monitor.
• Amazon Alexa and Ring: Kidde Smart Smoke and CO Detector with Ring, Kidde Hardwired Smart Smoke and CO.
• Tuya or Smart Life: Heiman C1-W.
• Apple HomeKit: No viable smart CO detector on the market in 2026. The Nest Protect was discontinued, and Matter support has not reached this category yet.

For professional monitoring, only the Kidde Ring model has a built-in path through Ring Protect as a low monthly add-on. Everything else relies on third-party services like Alexa Guard.

UL Certifications: 217 9th Edition and 2034

Any smoke alarm you buy should carry UL 217 9th Edition certification, which is the most recent standard and includes nuisance-alarm resistance tests against cooking smoke. Any carbon monoxide alarm you buy should carry UL 2034 certification, which sets the response thresholds (70 ppm for 1 to 4 hours, 150 ppm for 10 to 50 minutes, 400 ppm within 4 to 15 minutes).

The Heiman C1-W and C1-R carry UL 2034 5th Edition certification, which is the latest revision. The Kidde models carry both UL 217 and UL 2034 as needed. If a detector you are considering lacks either certification, walk away.

Lifespan, End-of-Life Indicators, and 10-Year Replacement

Every CO sensor degrades over time, which is why the industry settled on a 10-year end-of-life standard. After 10 years, replace the unit regardless of whether it still appears to work. Most detectors emit an end-of-life chirp at the 10-year mark, and the smart models push a phone notification when the countdown completes.

Budget for replacement as part of your 10-year cost of ownership. A battery-powered unit at the low end of our lineup needs three replacements across the decade for a multi-bedroom home; a hardwired unit needs one replacement per interconnected loop. The smart features do not change that math much.

Placement and Code Requirements (NFPA 72)

NFPA 72 requires CO detectors outside every sleeping area and on every level of the home. Detectors should be mounted on the ceiling or high on a wall, at least five feet above the floor, and away from fuel-burning appliances to avoid false alarms. For garage installations, look for cold-rated units because most CO sensors lose accuracy below 40 degrees Fahrenheit.

Placement is the most important thing you can read in this guide. A basic detector installed correctly will save more lives than an expensive detector installed in the wrong spot.

Frequently Asked Questions

Final Verdict: Which Smart Carbon Monoxide Detector Should You Buy in 2026?

If you live in a Ring or Alexa home and want the smoothest smart carbon monoxide detector experience, the Kidde Smart Smoke and CO Detector with Ring is our top recommendation. The combination of hardwired interconnect, free smartphone alerts, and an optional professional monitoring path gives you the most flexibility for the money. For a Google Home household replacing a discontinued Nest Protect, the First Alert SC5 is the most realistic drop-in option, even with its lower rating and false-alarm quirks. And for renters who want a no-subscription plug-in with bonus indoor air quality, the Kidde Smart CO Detector plus IAQ Monitor earns the best value badge in our lineup.

Whichever smart carbon monoxide detector you choose, install it according to NFPA 72 placement guidance, vacuum the vents every few months to prevent dust-induced false alarms, and budget for a full replacement at the 10-year mark. A connected detector that sends an alert to your phone while you are away is the difference between catching a CO event early and finding out too late. If you want to compare these picks against standard non-smart models, our roundup of the 10 best carbon monoxide detectors covers the wider category.