Waving arms trigger Nest Protect false alarms

Nest halted sales of its new Nest Protect Smoke and CO (carbon monoxide) alarms a month after their launch due to an issue with Nest Wave, an algorithm that allows users to 'wave to hush' the product. No customer incidents had been reported.

Wave was supposed to enable users to to silence a warning by waving their hand in front of the detector. But further lab tests by Nest revealed that it could be unintentionally activated during a real fire, resulting in a delayed response to real danger.

Nest pushed out a series of software updates, including one that disabled the Wave algorithm for existing users. A month later, the company recalled 440,000 of the devices. 

Google acquired Nest a few months earlier in January 2014.