By clicking a retailer link you consent to third-party cookies that track your onward journey. This enables W? to receive an affiliate commission if you make a purchase, which supports our mission to be the UK's consumer champion.
Which? investigation prompts 100s of unsafe CO alarms to be removed from sale: do you have one?
AliExpress and eBay have removed 438 listings for killer carbon monoxide (CO) and smoke alarms that Which? tests have found will fail to sound when they need to.
The online marketplaces took the action following our investigation, which revealed that seven potentially deadly unbranded carbon monoxide alarms and four unbranded smoke alarms were available through the sites. We've made all 11 products Don't Buys.
But not all carbon monoxide and smoke alarms are dangerous. We've tested 17 CO alarms so good at detecting the deadly gas that we've made them Best Buy carbon monoxide alarms. And two smoke alarms responded so quickly in our tests that we've made them smoke alarm Best Buys.
The seven dangerous carbon monoxide (CO) alarms
We're not even at the midway point of our latest round of CO alarm tests and we've already found seven unbranded alarms listed on eBay that simply can't detect CO reliably.
Testing is ongoing, but as we went to press each of the seven Don't Buy CO alarms has failed to detect the deadly gas at least once. And four are too quiet, with two registering just 70dB rather than the required 85dB. That's the difference between the noise a shower makes and that of a passing lorry, and it's a flaw that could cost you your life.
What to do if you have one of these alarms
If you have an unbranded alarm that looks like any of the seven dangerous products featured here, you will need to buy a new alarm as soon as possible.
Buy a well-known brand from a high street store or a reputable online retailer. We've only found dangerous alarms like these ones to be available through online marketplaces, such as eBay, AliExpress and Wish. Or check out our carbon monoxide alarm Best Buys to be sure you're buying a safe model.
Watch: How to buy a safe carbon monoxide alarm
The four smoke alarms that can't detect smoke
The smoke alarms story is just as worrying. Four unbranded alarms bought from eBay have failed to detect any smoke at all in our tests. So, whether we set fire to wood, cotton, plastics or solvents, these alarms just didn't work.
We reported on this problem earlier in the year: read about the four dangerous smoke alarms to avoid.
Again, if you have one of these products in your home, replace it immediately with one of the safe smoke alarms we've tested.
What is the scale of the problem on online marketplaces?
We searched eBay for CO and smoke alarms and found reams of listings for the 11 alarms mentioned above which have failed our tests and that can't be relied upon to detect smoke or CO. Since our latest investigation, eBay has now delisted all alarms we have identified as unsafe. However, while some have only recently failed our tests, we've uncovered at least five designs of alarms in previous years and these will have been known to eBay.
In all, 91 of the cheapest 200 CO alarms listed in 'Buy it now' auctions had failed our CO detection tests. And 50 were the type we first alerted eBay to three years ago.
The story is the same with smoke alarms. Fifty of the cheapest 200 listings were alarms that failed our smoke tests and 34 were alarms we've twice alerted eBay about, first in 2018 and then in May 2019.
AliExpress and Wish also list dangerous alarms
It's not just eBay allowing dangerous products to be listed on its site. On Wish, we found that 125 of the cheapest 200 CO alarms had failed our detection tests. And 27 of the cheapest 200 smoke alarms listed were products that had completely failed to detect smoke in our tests. Wish has known about them since at least May 2019, when we first alerted it to the problem.
AliExpress, another marketplace, was listing 134 dangerous CO alarms among the cheapest 200 on its site. And the site was just as bad for smoke alarms, having listed 163 dangerous alarms in its most affordable 200. However, like eBay, AliExpress has now removed those listings from its site as a result of our most recent investigation.
How to install smoke and carbon monoxide (CO) alarms
Here are our top tips to make sure your smoke and CO alarms keep you safe.
- Installation:Smoke alarms should be fitted close to the centre of the ceiling. The best place for CO alarms is high up in the same room as any potential CO source and at least one metre away from boilers, gas cookers or fires.
- How many do you need? One smoke alarm per floor is the bare minimum, but it would be ideal to have a smoke or heat alarm in each room. You should fit CO alarms in each room where there's a fuel-burning appliance.
- Fitting heat alarms: Heat alarms detect rapid rises in temperature and are useful for kitchens, where smoke from cooking would set off a smoke alarm. Check out our Best Buy heat alarms.
- What do beeps or chirps mean? If your alarm has replaceable batteries, chirping will mean that you need to replace the batteries. Doing this annually makes sense. Alarms with sealed batteries have fixed lifespans, so a frequent chirp means you'll need to replace the alarm.
- Checking and maintaining: Press the test button weekly to check your alarms are still working and lightly vacuum the holes in the case to help remove dust. Make a note of when you last changed the batteries. For a sealed battery alarm, write on the casing when the alarm needs to be replaced.
Which? saysu2026
Our challenge to eBay and also to AliExpress, Wish and other online marketplaces is simple: if the safety of customers is your main priority, then prove it by only allowing alarms to be listed on your sites that you know to be safe. It shouldn't be up to Which? to do this for you. If you can't block unbranded and dangerous alarms from being listed for sale, then don't allow that kind of product to be listed in the first place.
What the online marketplaces told us
AliExpress and eBay told us that customer safety is paramount and both have removed the listings we highlighted. eBay said it works with Trading Standards to ensure listings are legal and has asked sellers to warn buyers and issue refunds. AliExpress said it requires merchants to comply with local rules and regulations wherever it sells.
A spokesperson for Wish told us that it is working to remove the products from its platform.
