Installed the CO Guardian 353P-201 carbon monoxide detector. It connects to my GRT HXr EFIS via a serial connection. This gives me visual and audio warnings when the CO level is too high or when the cabin pressure hits 10,000, 12,500 and 14,000 feet. I'm not too interested in the pressure warnings, but it can't hurt to have the reminder.
The detector (it's the black box) is placed on the passenger side behind the main panel on the subpanel, below the (unused) map box cutout.
I decided to also add an indicator light only because the serial connection to the EFIS is through the right EFIS which is on my Avionics Bus 2. So if that bus is switched off, the EFIS won't be able to warn me visually or aurally (though the Guardian does have a built in 85 dB audible alarm). The LED indicator would anunciate high CO levels should either EFIS fail or be unavailable.
Here is the five-place circuit board for the new indicator lights (original four-place setup from 27-Oct-16 can be found here).
Though I had the board fabricated, I haven't yet installed it as I'm thinking it isn't really necessary unless the EFIS fails, in which case, I'd probably be looking for a place to land anyway.
Finally, since I didn't have an open fuse position on my fuse block, I decided that the CO Guardian would share power with the Aircraft Extras Fuel Guardian (bonus that they are both "guardians!). Thus, my new fuse block legend is below.
