Why is my carbon monoxide alarm beeping?

There are a number of possible reasons why a CO alarm could be beeping. The most important thing is to not ignore this, as they are warning signs of either a danger in the home or that an alarm needs maintenance.

Battery Powered - 10-year non removable lithium battery Mains Powered - 10-year lithium rechargeable, non-replaceable back-up battery

The CO alarm will beep and the amber LED will flash to indicate a fault condition.

If the alarm is beeps once with 1 amber flash, this indicates a low battery = replace the alarm

If the alarm beeps twice with 2 amber flashes, this indicates a faulty sensor = replace the alarm

If the alarm beeps three times with 3 amber flashes, this indicates the end of life of the alarm = replace the alarm

If the battery backup supply is depleted, the sounder will give one short chirp with one yellow LED fault indicator flash every 48 seconds. In this case check that the green LED power indicator is on continuously. If it is off, or flashing every 48 seconds, the Alarm is not receiving 230V AC mains power and is being powered by the battery backup. The chirp every 48 seconds indicates that the battery is depleted. The battery is not replaceable. Check fuses, circuit breakers and wiring to determine the cause of the interruption to the mains power. If in doubt, contact a qualified electrician. Once mains power is reinstated, the chirps should cease within 2 hours as the battery charges up. If the chirping persists for over 2 hours with the green light on, there may be some other problem with the Alarm.

The Alarm regularly checks the CO sensor and/or thermistor heat sensor for correct operation. If the Alarm has found a fault with the sensor, it will give 2 short chirps with 2 yellow LED flashes every 48 seconds. In this case, the Alarm must be returned for repair or replacement.

Once the Alarm passes its 10th year of installation, it will give 3 short chirps with 3 yellow LED flashes every 48 seconds to indicate it has reached its end of useful life. The entire Alarm must be replaced (Also check the replace by date on the label on the side of the Alarm). Disconnect the mains first and replace the Alarm.