Here is another angle on the CO detector. Shortly after purchasing my trailer, when it was just about 4 years old I heard the beep during the day. I have all the documentation so I read about this thing. They suggest that you test it every spring and at least once during each season. I also read that under certain conditions, like dusty roads, the sensor becomes affected by a covering of dust. The test actually shakes this dust off. I have been doing this for about 10 years now and it still is working. I certainly will replace it when it stops.
