Consumers are being warned to replace certain Firex brand carbon monoxide alarms and combined smoke/carbon monoxide alarms because of the potential for the units to shut down.

About 36,000 of the alarms, imported by Ohio-based Maple Chase Company, were sold across Canada between June 1, 2007, and Feb 1, 2008. About 16,000 were sold in Ontario.

The importer says the alarms may go into what it calls a "double chirp" fault mode in the presence of carbon monoxide. The owner's manual recommends consumer press the reset button when this happens, but doing so can turn the alarm off.

There have been no reported incidents related to the fault.

The recall involves Firex branded 10000 and 12000 series alarms with item numbers: 12000C and 12400C. Units with a manufacture date code prior to June 1, 2007, are not affected by this recall.

Affected units can be identified by the date code, which appears on the back of the unit. The format of the date code is a four-digit year, three-letter month, followed by the day (e.g., 2007 JUN01 for units manufactured on June 1, 2007).

Consumers should contact Maple Chase immediately to receive a free replacement alarm and make arrangements to return their affected alarm.

For more information, contact Maple Chase toll-free at 888-879-3906 between 8 a.m. and 6 p.m. CT Monday through Friday.

Maple Chase website