CO Detector

These seem to have a lifespan. From this Wiki article:

"When carbon monoxide detectors were introduced into the market, they had a limited lifespan of 2 years. However technology developments have increased this and many now advertise up to 7 years. Newer models are designed to signal a need to be replaced after that time-span although there are many instances of detectors operating far beyond this point."

It might be is time for a new one. It is trying to tell you so.

It may be that it can self test its sensor(s) and has decided it needs repalcement or tossing in the bin - suggest you go to the manufacturer/supplier.

Try vacuuming it before tossing it out. It could be that dust has settled on the sensor. Removing that dust might extend the life of the detector. You could also try putting it in your mailbox overnight. If, after all that, it still malfunctions, buy a new one. They're not that expensive anymore. Just don't toss it out without replacing it.

The ones I have (sorry, can't remember the brand) "expire" 10 years after initial activation. Then they start beeping & won't reset. We actually called the fire department to come check as they were going off through our whole house. (Our local gas company now charges ~$100.) They weren't aware of an expiration date, but when we got to the hardware store to buy new ones it stated it right on the package. They also have a place to write the date you activate them as a reminder. I'm guessing in about 9 years I am going to wonder why they are all going off again!

The manual for my "First Alert" brand detectors says "5 Years", and then the display will read "Replace" or something like that. If your model doesn't have a display, it might just be that it beeps to signal EOL (end of life).

Most manufacturers have product manuals online these days, have you looked for one?

Tom D.