Smoke alarms detect signs of fire. CO alarms detect carbon monoxide, an invisible poisonous gas. CO is not CO₂.
Why it matters: A working alarm gives you time to leave. A chirp may mean a battery problem or end of life, not just an annoying sound.
Written guidance reviewed: September 17, 2026 · Sources and equipment assumptions are below.
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Understand the job before starting
A test and a replacement or service check answer different questions. Use the exact alarm instructions.
A common mistake to avoid
Silencing an alarm is not proof that its underlying warning has been resolved.
Words used in this guide
Backup
A recoverable copy of data made for loss or damage. Read the example
Use what you already have. Check each item when it is ready.
Before you begin
A sounding alarm, smoke, gas odor, or possible CO symptoms means leave and call 911 from outside. Do not stay to diagnose it or assume it is a low battery.
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STEP 1 OF 5
Find and identify each alarm
Start here: Identify every alarm.
Example: Identify every alarm. Follow the written step.
Read-aloud is available in supported browsers; the written steps always remain available.
Look at the label to learn whether it detects smoke, CO, or both.
Record its model and replace-by date.
Ask maintenance to correct missing alarms; placement and interconnection rules vary.
Do not paint or cover an alarm.
Before moving to the next step
Check this specific result: I know what each alarm detects.
If that result is not true yet, leave the box unchecked. Write what is missing in your notes; use the official instructions below when the equipment or situation differs.
STEP 1 OF 5
Find and identify each alarm
Start here: Identify every alarm.
Example: Identify every alarm. Follow the written step.
Look at the label to learn whether it detects smoke, CO, or both.
Record its model and replace-by date.
Ask maintenance to correct missing alarms; placement and interconnection rules vary.
Do not paint or cover an alarm.
Before moving to the next step
Check this specific result: I know what each alarm detects.
If that result is not true yet, leave the box unchecked. Write what is missing in your notes; use the official instructions below when the equipment or situation differs.
STEP 2 OF 5
Learn the sounds from the manual
Start here: Learn this alarm sounds.
Example: Learn this alarm sounds. Follow the written step.
Read the exact meaning of the beep pattern, spoken message, and indicator lights.
Many smoke alarms use three repeating beeps and CO alarms four, but models differ.
A periodic chirp can mean low battery, fault, or end of life.
Use the label, not a guess.
Before moving to the next step
Check this specific result: I know the model-specific alert meanings.
If that result is not true yet, leave the box unchecked. Write what is missing in your notes; use the official instructions below when the equipment or situation differs.
STEP 3 OF 5
Use the TEST button
Start here: Use the TEST button
Illustration: Test smoke and CO alarms. Read the steps for your exact task.
Notify housemates before testing.
Press TEST according to the manual, commonly at least monthly.
Do not test with a flame, vehicle exhaust, or spray not approved by the maker.
If it fails, arrange replacement immediately.
Before moving to the next step
Check this specific result: The alarm passed its recommended test.
If that result is not true yet, leave the box unchecked. Write what is missing in your notes; use the official instructions below when the equipment or situation differs.
STEP 4 OF 5
Replace the correct part
Start here: Fit only the required part.
Example: Fit only the required part. Follow the written step.
Use exactly the battery type the maker permits.
AA, 9-volt, and rechargeable cells are not interchangeable recommendations.
A sealed long-life alarm has a battery you do not replace; replace the whole alarm at its end of life or failure.
A hardwired alarm may have a backup battery.
Before moving to the next step
Check this specific result: My battery or whole-alarm replacement matches the manual.
If that result is not true yet, leave the box unchecked. Write what is missing in your notes; use the official instructions below when the equipment or situation differs.
STEP 5 OF 5
Plan the response
Start here: Practice the escape plan.
Example: Practice the escape plan. Follow the written step.
Practice two ways out when possible and a meeting place.
Never disable an alarm to stop cooking alerts; use ventilation and the approved hush button only when there is no danger.
Never run a vehicle in a garage—even with the door open.
Before moving to the next step
Check this specific result: My household knows the exit plan.
If that result is not true yet, leave the box unchecked. Write what is missing in your notes; use the official instructions below when the equipment or situation differs.
Pictures for this guide
Picture 1 of 5 · Find and identify each alarm
Find and identify each alarm: Smoke and CO are different. Read each label and expiry.
For: Find and identify each alarm
Illustrations show examples of the actions above. Follow your equipment’s instructions.
Notes about these pictures
Look at the label to learn whether it detects smoke, CO, or both. Record its model and replace-by date. Ask maintenance to correct missing alarms; placement and interconnection rules vary. Do not paint or cover an alarm.
A sounding alarm, smoke, gas odor, or possible CO symptoms means leave and call 911 from outside. Do not stay to diagnose it or assume it is a low battery.
Was this step clear?
Flag “Find and identify each alarm” for review. We save the guide and step identifiers with your account to limit duplicates, not your private notes.
What to look for: Watch the smoke-alarm test example. CO alarms and sealed-battery models need their own instructions; safe testing does not mean disabling an alarm.
Link details checked 2026-10-03. Video availability and equipment menus can change.
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How to use the video with this guide
Read “Before you begin” first. Watch the relevant part, pause, then return to the written step and its completion check. Use captions and playback speed if they help. A demonstration may cover only part of the task or show different equipment.
Your model’s instructions and current official guidance take priority. For urgent problems, follow the stop instructions without waiting to watch a video.
For this guide, the final result is: My household knows the exit plan.
A concrete way to approach this task
Record each alarm’s location, the test result, and the replacement or service information from its instructions.
What if I cannot complete a step?
If a test result is unclear or an alarm keeps sounding, check its specific instructions. Do not treat silencing it as proof the underlying issue is resolved.
Identify the exact step: “Find and identify each alarm.” Record what you tried, what happened, and which item or model you used. Ask for help with that specific problem rather than repeating an unsafe or unsuccessful action.
A sounding alarm, smoke, gas odor, or possible CO symptoms means leave and call 911 from outside. Do not stay to diagnose it or assume it is a low battery.
Connect this skill to everyday life
Write down the total move-in cash and monthly costs before applying. Ask which charges are required and which are optional.
Advertised rent is not necessarily the whole monthly cost. A refundable deposit still needs cash now. An application does not mean you have a signed lease.
