On 19 Sep 2008 23:11:46 GMT, Jim
wrote:

Came home today to discover that my First Alert model FCD4 was acting
strangely. Single chirp every minute or so. Looking closely at the
display was the "err" message.

I'm guessing it is one of two factors. #1 being they are cheaply made
and simply don't last more than a couple years. #2 being the sensor is
dirty causing the error message. If so how does one clean it? Would
compressed do?

Howdy,

I will add something to the other comments you have seen...

We had a similar problem (not with a CO, but with a smoke)
and could not find the cause of the chirp.

As it turns out, when these things are hard wired, they talk
to each other, and the unit chirping was not the unit with
the failed battery.

It took us quite a while to sort out, but you might want to
consider that possibility.

All the best,
--
Kenneth

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