Unlike the smoke detector, the carbon monoxide detector does not have a crisis test to perform

Fire Alarm General Discussion
1

(Because you would never want to emit carbon monoxide into a house consciously.)

This is what it says online on a certain site. The smoke detector can be detected with smoke (called a crisis test), but the carbon monoxide detector is only to be tested with the test button.

2

Wondering if a candle can generate enough CO to activate the detector…
Candles burn with bright flame and lots of soot, which are characteristics of fuel-rich combustion. Theoretically they generate CO.

3

On the contrary, canned “bump gas” for household CO alarms is a thing, and is safe when used as directed: https://www.homedepot.com/p/MTI-Industries-Carbon-Monoxide-Test-Gas-19-oz-Aerosol-Can-SA-HHTG-1/312461834