Carbon monoxide (CO) alarms unreliable after seven years?

The sensor on most detectors are life limited to ten years. The legal department probably makes them put 7 years on the box.
It is the sensor that wears out in ten years.

Thank you for your answer, Tropical_Willie. I’m surprised that I didn’t hear about this before. I don’t believe it was written in the instructions and I’m pretty good about reading those when I purchase something… Do other people know about this?

Yes, there is some chemical/substance in them that has a 7-yer life span.

At work, we have CO sensors that are still working after 12 years. Maybe the industrial versions don’t have the built in obsolescence.

Thank you for your input, filmfann. How can they tell that the CO sensors are still working?

@selfe Press the “TEST” button should give you a response, some are a vocal and some are a series of beeps. The beeps on some are a code to status of detector ( low battery, sensor bad, etc. ). Check the internet for a owners manual.

As I recall, we use a Sierra 2440 monitor for the underground vault environmental controls. I believe it has a self test on the CO sensor.