The answer to 'why is my carbon monoxide detector burning smell' is that a burning or acrid smell coming from your carbon monoxide (CO) detector is usually a sign that the detector is malfunctioning and needs to be replaced. This could indicate an issue with the internal components or that the detector has reached the end of its lifespan.
Carbon monoxide detectors are designed to last 5-7 years on average. Over time, the sensors and internal mechanisms can degrade, causing the detector to malfunction and potentially emit a burning or chemical smell. This is a clear sign that the detector is no longer functioning properly and needs to be replaced immediately to ensure your home's safety.