The answer to 'carbon monoxide detector gets hot' is that a carbon monoxide (CO) detector getting hot is a sign of a potential issue that requires immediate attention. This could indicate a problem with the detector itself or a larger issue in your home's electrical system.
Common causes for a CO detector getting hot include a malfunctioning detector, a problem with the wiring or power supply, or high levels of carbon monoxide in the air. If your CO detector is getting hot, it's important to take action right away to identify and address the underlying issue.