Pressing the test button allows you to check if the device is powered on, as well as check the performance of the speaker. While this may be the only way for you to manually test the natural gas alarm, internally the natural gas alarm is performing self-tests that check a variety of sub-circuits in the natural gas alarm, including the temperature and humidity sensor, and the methane sensor itself. If something is found wrong with one of these sub-circuits, the Trouble (Yellow) LED will begin to blink 3 times every 10 seconds, and the audible alert will beep 3 times and say “Detector error” once every minute. This natural gas alarm should NOT be used as a short-term testing natural gas alarm. In other words, you should not test it by intentionally leaking gas, either via a stove, a pilot light, or any other gas source. Not only is this not the intended operation of the natural gas alarm, but this can cause a very dangerous situation that could have otherwise been easily avoided.