I have mine wired to the GDU and to one of the alert inputs in my audio panel. I get a "CO sensor OK" audio on boot up, and "Cabin Altitude" at 10k'? The GDU shows CO PPM and I think? will throw an alert at a certain threshold. Never wired in the LED.
RV-9A - started 01/2015, completed 07/19/2018, 500hrs 03/14/2020
RV-10 - started 04/2020