My idea of how a small investment might just save you from a silent killer.
Carbon Monoxide has always been a concern of mine over the years. When one of my first trucks (not a Freightliner) gave me severe symptoms of recurring headaches, it was narrowed down to an exhaust leak leeching dangerous carbon monoxide into the cab, both while running and during any sleeper berth idle time. As lucky as I was to have caught the root of the problem in time, this idea might have saved me the danger and hassle of finding it the way I did!