How do I know the battery backup is working?

Press the test button — it tests both AC power detection and battery backup. If the backup battery is low or missing, the CO606 will emit a distinct low-battery chirp pattern (different from the alarm and end-of-life signals).

Can I use a rechargeable 9V battery in the CO606?

First Alert recommends standard alkaline 9V batteries only. Rechargeable batteries have a lower voltage output that may not provide sufficient power for reliable backup operation.

What's the end-of-life signal?

After approximately 7 years, the electrochemical sensor degrades to a point where accurate CO detection is no longer reliable. The CO606 emits a specific chirp pattern (typically 5 chirps every 30 seconds) that differs from the low-battery or CO alarm patterns, indicating the unit should be replaced. Do not silence and continue using a unit that has issued an end-of-life warning.

Is the CO606 interconnectable with other alarms?

The CO606 is not designed for hardwired interconnect. For interconnected systems (where all alarms sound when one detects CO), look for First Alert models with the OneLink wireless interconnect feature or hardwired interconnect capability.

How does it meet UL 2034?

UL 2034 is the Underwriters Laboratories standard for single and multiple station CO alarms. It specifies alarm thresholds that prevent nuisance alarms at low CO levels while ensuring alarm at concentrations that pose health risk. The CO606 is UL 2034 listed, satisfying the requirements referenced by NFPA 720 and most state CO alarm codes. Related Products & Guides co detectors first alert carbon monoxide alarms detectors home safety best carbon monoxide detector 2026 best smoke detectors 2026 First Alert GCO1 Combination Carbon Monoxide a First Alert CO710 10-Year Sealed Battery Carbo First Alert CO615 Plug-In Carbon Monoxide Alar

Where should a carbon monoxide alarm be installed?

On every level of the home and outside each separate sleeping area. CO mixes with air rather than rising like smoke, so height matters less than proximity to where people sleep. Keep it away from fuel-burning appliances and vents, which cause nuisance alarms.

How long do CO alarms last?

The electrochemical sensor is consumable - typically 7 to 10 years from the date of manufacture, not from the date of installation. Most units now announce end-of-life; when they do, the unit is replaced, not re-batteried.

What should I do when it sounds?

Get everyone into fresh air first, then call the fire service or the gas utility from outside. Do not re-enter to hunt for the source and do not open windows first - ventilating before the responder arrives can mask the reading they need to find the fault.

Is a combination smoke and CO alarm as good as two separate units?

For coverage, yes, and it removes one ceiling fixture. The trade-off is lifetime: the two sensors age differently, so the combination unit is retired on the earlier of the two dates.

Does this replace calling emergency services?

No. First aid supplies stabilise and buy time. Any loss of consciousness, breathing difficulty, uncontrolled bleeding, a chemical exposure to the eye, or a burn beyond a small superficial area is a call for professional help first.

Where should it be stored?

Somewhere unlocked, signposted and reachable in seconds. A kit in a locked office is not readily available under 1910.151, and neither is one behind a stack of boxes - which is the usual real-world failure.

Where do the specifications on this page come from?

From the manufacturer's published listing for this model and from the text of the standards cited. WC Safety does not test emergency equipment, and where a fill list or a class is not published, this page says so rather than assuming it.

First Alert CO606 Plug-In Carbon Monoxide Alarm with 9V Battery Backup

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First Alert CO606 Plug-In Carbon Monoxide Alarm with 9V Battery Backup

Name: First Alert CO606 Plug-In Carbon Monoxide Alarm with 9V Battery Backup
Brand: First Alert
SKU: CO606
Price: 23.99 USD
Availability: InStock

First Alert SKU: CO606 Carbon Monoxide Alarm

★ ★ ★ ★ ★ 4.7 (22897 Amazon customer ratings)

$23.99

Final price set by Amazon · may vary

EDITORIAL REVIEW — First Alert CO606 Plug-In Carbon Monoxide Alarm with 9V Battery Backup Assessed on the standards the product is actually certified to and on how the format fits a working shift, by Steven Eaton, WC...

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battery backup carbon monoxide alarm CO detector CO606 First Alert plug-in

EDITORIAL REVIEW — First Alert CO606 Plug-In Carbon Monoxide Alarm with 9V Battery Backup

Assessed on the standards the product is actually certified to and on how the format fits a working shift, by Steven Eaton, WC Safety editor.

Short answer: The CO606 is the best of both worlds in First Alert's lineup — it plugs into a standard 120V outlet for permanent installation, but the included 9V battery backup keeps it running during power outages. This matters because power outages are exactly when CO risk spikes: people run generators indoors, use propane heaters, or light candles near gas appliances. If you're choosing between the CO600 and CO606 for a permanent installation, the CO606 is the right call.

Key specs at a glance

Power: 120V AC plug-in primary power
Backup: 9V battery — maintains protection during power outages
Sensor: Electrochemical CO sensor
Alarm Output: 85dB at 10 feet
Controls: Single test/silence button
Listing: UL 2034
Warranty: 7-year limited

first alert co606 plug-in carbon monoxide alarm with 9v — what the listing actually specifies

Why Battery Backup Matters for CO Detection

A portable extinguisher is for an incipient fire only. OSHA 29 CFR 1910.157 and NFPA 10 both scope portable units to a fire still small enough to be approached safely with an escape route at your back. If it has spread beyond that, the correct action is to evacuate and call the fire service.

Generator use is the #1 source of CO fatalities in the US

When the power goes out, households turn to generators, propane heaters, and gas stoves. These devices produce CO. A plug-in CO alarm with no battery backup goes offline at exactly the moment the risk increases. The CO606 addresses this directly — its 9V backup battery activates automatically when AC power is lost.

First Alert CO Alarm Comparison

Model	Power	Outage Protection	Warranty	Best For
CO400	9V battery only	Yes (is battery)	5 yr	Outlet-free locations, RVs, supplemental
CO600	120V AC	No	7 yr	Permanent install, no battery maintenance
CO606 ★	120V AC + 9V backup	Yes	7 yr	Recommended permanent install — full coverage

Installation Guide

Install the 9V backup battery before plugging in
Plug into a standard 120V outlet — unit activates immediately
Press the test button to verify alarm function
Mount height: 5 feet from floor on walls near outlets, or on outlet covers at outlet height — CO disperses throughout the room, not just at ceiling level
Required locations: outside each sleeping area and on each level of the home (NFPA 720)
Replace backup battery annually — the unit will chirp to signal low battery

More from our Carbon Monoxide Alarm reviews

If the decision is still open, the comparisons in 10 year sealed vs replaceable battery smoke alarms, best battery smoke detector 2026, best carbon monoxide detector 2026, best economical smoke detector 2026, best fire extinguisher for home narrow it down.

Alternatives at the same protection level are listed in abc dry chemical extinguishers, carbon monoxide, carbon monoxide alarms detectors.

Written by Steven Eaton, WC Safety editor. WC Safety is an independent PPE review site, holds no inventory and sells nothing directly; Amazon links are affiliate links that earn a commission at no cost to you and never affect the assessment. This page is not medical, legal or regulatory advice.

These cover the questions this page does not: best fire extinguishers 2026, best first alert smoke detector 2026, best hardwired smoke detector 2026, best kidde smoke detector 2026.

To see what else meets the same specification, start with carbon monoxide gas monitors, combo smoke co alarms.

For the surrounding context, see best n95 mask for wildfire smoke, best photoelectric smoke detector 2026, best smart smoke detector 2026, best smoke detector for kitchens 2026.

Neighbouring categories worth ruling in or out first: extinguisher cabinets, fire escape hoods.

Brand / Vendor

First Alert

Model / SKU

CO606

Product Type

Carbon Monoxide Alarm

Price

$23.99 (Amazon)

Rating

4.7 / 5 — 22897 Amazon ratings

Availability

Check current availability on Amazon

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Customer Reviews

★★★★★4.7 / 5· 22,897 ratings on Amazon

★★★★★

Necessary important easy task!

My old units were 10 yrs old. Needed to be replaced and updated. This is not something to be ignored!Very easy to follow the directions for set up before plugging in. Takes a few minutes with indicator lights and beeps to keep you on track. Since I replaced them they've been trouble free. No problems.

Verified Purchaser · May 24, 20 · ✓ Amazon Verified Purchase

★★★★★

Perfect Product Design & Packaging

These manufacturers know how to put a great product together and also how to package it. Our previous First Alert carbon monoxide detector from 2019 started chirping 5 chirps. A Google lookup indicated it was indicating the end of its service life. Wow! Pretty cool. So I stayed with First Alert for replacing our two units. Both arrived in under a day. And you know how most plastic wrapped items are difficult to open without slicing your fingers? Not these. The back of the package has a perforated pulldown tab to open easily. And they even provide a new battery. Totally legit Company placing the customer FIRST, for real.

Verified Purchaser · May 19, 20 · ✓ Amazon Verified Purchase

★★★★☆

As per my research This is a UL Certified it meets US safety standards

Read this if you want to save your time reading the too much info in the manual. Its overwhelming. This kind of stuff there should be a separate manual that features only the important instruction.- first and foremost 4 star only coz I wanted to buy the 3 pcs pack but good thing Ive read some comments with same complaints that they bought 3 pcs but they received only 1 pc. That must be a hassle and inconvenient to raise a complaint so I just bought 2 separate item and I am planning to buy another 2.- REASON WHY I BOUGHT THIS BECAUSE IVE READ: that First Alert is a reputable brand known for fire and CO safety products. Battery Backup: Works during power outages essential for 24/7 protection.Easy to install, no hardwiring needed.And the most important is it is "UL Certified" it Meets safety standards set by Underwriters Laboratories. Compared to other co detectors in amazon. These certifications mean the CO detector:•Has passed rigorous, standardized safety tests•Will reliably detect dangerous levels of carbon monoxide•Won’t give false alarms or miss actual dangerAnd when you buy this whether u like it or not you have to put the battery first and plug it. Coz if you dont put the battery and just plug it directly there will be a chirp sound every 30 seconds or so, and I found out thats an indication you need to install the battery. My bad I did not read the manual coz it overwhelms me a lot coz its too much to read for a supposed to be direct instructions only.So I tested my 2 first alert and it works. And you have to test it at least once a week. How I know this really works? I dont know I just have to trust the brand. And not wishing to have CO leak in our house. But this will bring us peace of mind knowing we have a CO detector at home esp so many sad cases about co leak in the house and people die. BE CAREFUL Y'ALL!

Verified Purchaser · March 31, · ✓ Amazon Verified Purchase

★★★★★

A must have safety item for hallway in home.

I got this item to replace a 10 year old same model First Alert carbon monoxide detector. Old detector working fine but I decided to replace it. Fortunately I never had a CO leakage but I checked the test button every few weeks to ensure it was working.

Verified Purchaser · May 9, 202 · ✓ Amazon Verified Purchase

★★★★★

Have used this exact model before, it lasts a good long time.

I had this exact model 15+ years ago. Test it every 6 months, and when it failed the recent test, checked the 9V battery, which was still good. Ordered this exact one online, put the battery in and plugged it in, tested, working.These are easy to use, you don't really need instructions. Always good to have one in the garage and main area of your house.Hoping it lasts another decade plus.

Verified Purchaser · June 2, 20 · ✓ Amazon Verified Purchase

★★★★★

Easily blends in

Smaller design really helps to blend the device into the wall. Plug and play, very easy.

Verified Purchaser · June 12, 2 · ✓ Amazon Verified Purchase

Showing 6 of 22,897 Amazon reviews.

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