"There are more than 38 million residential carbon monoxide detectors installed in the United States. We tested 30 detectors in use and found that more than half failed to function properly, alarming too early or too late. Forty percent of detectors failed to alarm in hazardous concentrations, despite outward indications that they were operating as intended."
If you look at Figure 2, some of the sensors failed safe (generators die) others unsafe (people die)
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3222366/
"There are more than 38 million residential carbon monoxide detectors installed in the United States. We tested 30 detectors in use and found that more than half failed to function properly, alarming too early or too late. Forty percent of detectors failed to alarm in hazardous concentrations, despite outward indications that they were operating as intended."
If you look at Figure 2, some of the sensors failed safe (generators die) others unsafe (people die)