Exhaust Smell and CO in Cabin

Thank you for correcting my error, regarding the density of CO.

I will have to rethink the location of my CO detector  currently in the footwell.

It should be closer to the entry point of let's say the cabin heat vent if it is heated by a shroud around the muffler. Early warning is best. Planes like the Flight Design have way to much air movement up by their head and the heat coming in is down by their ankles so placing the CO detector lower down by their knees gives them some warning before it's up in their face. First warning sign may be a feeling of air sick symptoms and you would really know it was CO.

Interesting comments about CO detection. My new RAAus digital detector has a small chain which I hook around a guarded switch low down on the instrument panel so it is always visible in an instrument scan. The chain allows removability to occasionally wave around the cockpit to check for any potential leak sites, none so far.  I believe having the detector quite visible is the key.

My commonly available Co detector, is designed for use in caravans/mobile homes/ boats, is battery operated (good for about 2 years) has a visual  & audible (? don't know how this would work in a small aircraft) alarm. It also has a memory that can be interrogated for Max CO ppm.  No idea how sensitive it is but advertised as meeting a range of standard's. About X2 the price of a yellow tab but does not require replacing at very short intervals.