CO will slowly suffocate you if the concentration is too high so you need to go somewhere you will get fresh air.

So when it beeps, get out. Keep the doors open, too. If that's not an option, stick your heard out of a window and stay there. Call 112, 999, 911 or whatever number is relevant to you, depending on where you're from.

They will try to locate the problem and air out your entire house in the process.