alarm went off 4 beeps stopped a few hours

[Guest f]

Hi Mt alarm went off 4 beeps at 9pm stooped..  went off around 11pm then last time was at 430am. Date says 2015. I live in an apt and asked my neighbors if they had this happen they said no. Everything is turned off we are fighting a cockroach infestation because of unit upstairs could this be the reason? We don't clean the alarm because we didn't know we had to do it.. each unit has own furnace in tbe units which is locked and landlord hasn't serviced since 2020. What could this mean? We called fire department but waiting for them so in mean time since were waiting outside I figured I'd ask on here. Thank you

[green-foam]

As you asked over a week ago (This forum has become very slow as of late) I presume the fire dept have been and gone?

I would be concerned about the date on your CO detector, be it that is the installation date or the end of life date it needs changing.

I assume you are in America? this is a UK forum.