How to Fix a Chirping Smoke Detector

Place the step stool or ladder below the smoke detector, which will typically be mounted high on a wall or the ceiling.

Twist the bottom half of the smoke detector about 1/2-turn counter-clockwise by hand to release the lower section of the detector from the mounting bracket that secures it to the wall or ceiling.

Remove the battery from its compartment by detaching the plastic cap on top connected by two wires to the battery. Almost all smoke detectors use a 9-volt battery with two posts on top.

Connect a new battery by aligning the two posts on the battery with the posts on the cap connected by two wires to the smoke alarm. The large battery post connects to the smaller post on the cap.

Reinsert the battery in its compartment and reattach the smoke detector to the mounting bracket by turning the lower half 1/2 turn clockwise around the bracket.

Check the wires connecting a hard-wire smoke detector to the building’s electrical system. A loose wire on a hard-wired detector may cause the unit to chirp. Reattach the wires to the detector by pushing the metal clips firmly onto the pins on the detector.

Clean the contacts on the end of the wires and the pins on the smoke detector by rubbing a cotton swab dipped in alcohol on the metal parts (alcohol is a weak solvent that can help remove corrosion).

Detach and replace the smoke detector with a new unit if the old detector continues chirping. Smoke detectors, like other products, will wear out eventually. A hard-wired detector reattaches to the wall or ceiling wires with the metal clips as described in step 6. Battery-only powered units simply require a fresh 9 volt battery.