Why does my carbon monoxide detector beep more than my mother-in-law?
While a beeping carbon monoxide detector can be frustrating, it’s actually trying to keep you safe.
These alerts are your home’s way of telling you something isn’t right, whether it’s a low battery, a dirty sensor, or a dangerous buildup of carbon monoxide.
In this guide, we’ll go over:
- Nuisance ‘chirps’ versus a real alarm
- Actionable steps if there is a genuine hazard
- Tips to diagnose nuisance chirping
- How to test a carbon monoxide detector (spray can tester)
- And more…
Let’s get started!
The Difference Between A Beeping Alarm And Nuisance Chirps
Not all sounds from a carbon monoxide alarm signal an emergency. Understanding the difference between a full alarm and a nuisance chirp can help you respond appropriately and stay safe.
- 4 LOUD beeps + pause (and continuously repeats): This pattern signals that dangerous carbon monoxide is detected; evacuate immediately. Read the section below on what to do.
- 1 chirp every 30–60 seconds or irregular beeps: Low battery, end-of-life warning, dirty vent, or possible malfunction. You can temporarily silence nuisance chirps by pressing the test/silence button on the CO alarm. Jump to this section.
A smoke/fire alarm going off will have a different siren which will be fast and continuous beeping — there is no pause. You can read our guide on diagnosing fire alarm chirping here.
How To Silence Beeping Or Chirping (Hush Button)
The silence or test button, usually located on the front of your carbon monoxide alarm, lets you temporarily pause nuisance beeps and to test that it’s working. Below are a few tips on using it:
- Use the silence/hush button only for non-emergency situations, like nuisance chirps.
- Press briefly to pause beeping
- You can verify the alarm is functioning correctly by pressing it also.
- Never press silence during a real CO alarm, always evacuate first.
How To Handle A Beeping Carbon Monoxide Alarm (Possible Emergency)
The average carbon monoxide alarm emits 4 LOUD beeps, a brief pause, then 4 more beeps, repeating continuously, when it detects hazardous levels of the odorless gas.
Here are a few steps to take if your carbon monoxide alarm goes off…
Step #1. Evacuate The Home
If the CO alarm is making 4 LOUD beeps, followed by a brief pause, and then repeated by four loud beeps — everybody should evacuate from the home (including pets) and get to fresh outdoor air.
Carbon monoxide exposure can build up quickly in the body which leads to confusion and dizziness, making evacuation more difficult.
Even if you open up windows and doors, carbon monoxide gas can linger in the home so it’s critical to get to fresh air. If the CO detector is near a gas or propane-fired appliance, do not linger in that area.
Step #2. Call 911
The safest approach is to call emergency services from your cell phone (or a neighbor’s) only after evacuating outdoors.
They will be able to verify if there are dangerous CO levels in the home and check any suspected appliances.
Clearly tell the 911 operator that the carbon monoxide detector has gone off and your exact address. If anyone is experiencing carbon monoxide symptoms, tell the 911 operator while you are on the phone.
Common Carbon Monoxide Symptoms
- Dizziness
- Headache
- Nausea/Vomiting
- Confusion
- Shortness of Breath
- Fatigue
Emergency services — usually the fire department — have specialized equipment to detect carbon monoxide and will likely determine the source of the CO leak.
If you waste time trying to pinpoint the source of a carbon monoxide leak, it may be too late. It’s best to let the professionals check out your home before you re-enter.
The Need For Pure Oxygen
The typical treatment for CO poisoning is giving the patient 100% oxygen through a mask. However, severe cases may require hyperbaric oxygen therapy.
Carbon monoxide gets attached to hemoglobin in the blood, so inhaling pure oxygen helps to quickly reduce the CO in your red blood cells and increases oxygen to body tissues.
Step #3. Fix The Faulty Appliance
After inspecting your home, emergency services may identify the gas or propane appliance responsible for the carbon monoxide leak.
Besides gas appliances, it’s also possible that a car was accidentally running in the garage or someone was running a generator in or near the home.
Some of the most common causes include:
- Malfunctioning gas furnace or boiler (poor venting or cracked heat exchanger)
- Car left running in an attached garage, even with the door open
- Gas water heater with a blocked or damaged vent pipe
- Fireplace or wood stove with poor draft or a blocked chimney
- Gas dryer or other fuel-burning appliance with a clogged or disconnected exhaust
- Portable generator used indoors or too close to windows or doors
If emergency services have cleared you to re-enter the home, they may instruct you to avoid using the defective appliance until it’s repaired.
They may have turned off the gas supply to that appliance or possibly turned off gas to the entire home. You will need to contact a licensed HVAC company or contractor for emergency repair.
How To Fix Nuisance Beeps Or Chirps
Occasionally, a carbon monoxide alarm may beep or chirp even when there is no actual danger. These alarms use a series of chirps, beeps, and light patterns to communicate their status.
Just remember that the real alarm is four LOUD beeps followed by a brief pause, and then four more loud beeps — repeating continuously.
If it’s not an actual alarm, these little alerts or ‘chirps’ usually mean something needs attention, like a low battery, a dusty sensor, or that the unit is getting old.
Below are the most common reasons for these nuisance beeps and how to deal with them as well as a sample troubleshooting table for the First Alert (CO606) alarm. You will need to check with your particular model’s manual for confirmation however.
| Status | LED Indicator | Horn |
| Carbon Monoxide Detected | Red LED flashes at same pattern as horn | 4 loud beeps, pause, and then repeats |
| End of Life Signal | The light flashes (RED) | 5 chirps every minute |
| Low Battery | n/a | 1 chirp every 60-seconds |
| Malfunction | The light flashes (RED) | 3 chirps every minute. |
| Power Outage With Battery Backup | LED shines continuously | Silent |
Fix #1. Replace The Battery
The most common cause of a carbon monoxide beeping or chirping (not an actual alarm) is due to a low battery.
CO alarms have an internal program that beeps or chirps about once a minute to signal the homeowner to change the battery. A low battery may not have enough power for the carbon monoxide alarm to detect dangerous CO levels in the home — leaving you unprotected.
Some CO alarms will need to have their battery replaced at least every 12 months. Sealed CO alarms don’t allow battery replacement, so the entire unit should be replaced every 7–10 years.
Type of Batteries
CO detectors typically use a single 9-volt battery, or 2-3 AA or AAA alkaline or lithium batteries. If at all possible, use the highest quality name-brand batteries in your unit such as Energizer, Duracell, or Rayovac.
You may need to use lithium batteries for CO detectors in areas with extreme temperature changes, like unfinished basements or attics. It’s best to use the type of battery recommended in the manual.
6 Steps To Replacing The Battery
- Shut Off Breaker: If the CO detector is hardwired with battery backup, first shutoff power to the detector at the electrical panel.
- Remove Unit: Twist or disconnect CO alarm from wall bracket to access the battery compartment.
- Remove Battery Cover: Depending on the unit, slide or press the battery cover to open it.
- Replace Battery: Remove the old battery and install the new ones, make sure they are in the same direction, matching the +/- on the battery ends.
- Reinstall Cover: Snap or slide back in the battery cover.
- Test Alarm: Flip the breaker back on at the panel if you turned it off. Briefly press the test button to make sure the CO alarm works. You may need to hold down the test button for a few seconds.
Fix #2. Replace The Unit
Carbon monoxide alarms have a limited lifespan, typically lasting between 5 and 10 years. When the unit gets old, the chemical sensor that detects the odorless gas can no longer function reliably.
An internal program gets triggered and it either starts chirping (such as 5 chirps per minute), flashes a particular color (solid or flashing red) — or show ERR or END if there is a digital display.
If you change the battery, and the unit keeps chirping, this is another sign that it may be the entire unit that needs replacement.
To accurately interpret the chirp, I recommend check the manual to confirm the end-of-life signal to avoid wasting money on a new unit. You can also check the back of the unit for a manufacturing date.
6 Steps To Replacing The CO Alarm
- Confirm End-of-Life: Check the back of the CO detector for a manufacturing date or a handwritten date of when it was installed. I recommend verifying the chirping pattern (1-5 beeps per minute), flashing red LED light, END on digital display with the model’s manual.
- Purchase Replacement: Buy a model that matches your existing unit for hardwired/battery combo or if it’s just battery-powered. You may want to buy the same model so you can just install it into the existing wall bracket.
- Remove Old Unit: If hardwired, first shutoff power at the breaker. Twist or slide off the CO detector from the mounting bracket. If hardwired, disconnect the wiring or quick connect (wiring harness).
- Install Wall Bracket: If you purchased a different model, you will have to remove the old wall bracket and install the new one.
- Install New Detector: Put in the correct batteries, and install the new CO detector onto bracket. Don’t forget to connect the wiring if it’s hardwired.
- Test Unit: Press the test button to make sure the CO alarm is working.
Fix #3. Clean The Vent
A dirty CO detector may activate its built-in alert system, causing the unit to chirp.
A blocked air vent is hazardous because it may block carbon monoxide gas from properly triggering the alarm.
Some common items that can block the air vent:
- Dust buildup and household dirt
- Cobwebs or insect nests
- Pet hair and dander
- Paint or overspray from home projects
- Furniture, curtains, or décor placed too close to the alarm
I recommend checking the manual to see if your CO alarm provides a ‘blocked airflow’ or ‘dirty unit’ alert — some models don’t signal this condition at all. You can also do a visual check of the CO alarm to see if it’s obviously dirty.
The biggest hazard with cleaning CO alarms is that if you use harsh chemicals or heavy-handed cleaning methods it can damage the detector. Ideally, use gentle cleaning methods and don’t allow any liquids to seep into the unit.
6 Steps To Cleaning CO Alarm
- Remove Unit (Optional): You may want to remove the unit to clean it but cleaning it in place is an option if it’s accessible. Otherwise, first shutoff power at the breaker if it’s hardwired.
- Use Vacuum: Use a vacuum brush attachment to clean the exterior and focus on any vent holes.
- Wipe Down Exterior: Use a slightly DAMP cleaning wipe or cloth to wipe down the exterior. Don’t use anything wet that may leak liquid into the unit, possibly damaging it.
- Compressed Air: If you have one, use a can of compressed air to briefly blow into the vent holes to dislodge any fine dust or particles that the vacuum may have missed.
- Check Battery Contacts: Open up the battery compartment and make sure it’s clean and free of corrosion.
- Reinstall And Test: Hit the test button after cleaning to make sure it’s still working.
Fix #4. Do A Hard Reset
Sometimes, resolving a persistent CO alarm chirp only requires performing a hard reset.
Similar to a computer or television, you may just need to shut it off and turn it back on for it to work properly.
Hard resets clears the CO detector of temporary glitches and can eliminate chirping. If you checked the battery, and that the chirping isn’t an end-of-life signal, you may want to try a hard reset to see if it fixes the beeping.
To do a hard reset, you’ll need to disconnect any wiring (if hardwired) and remove the battery — removing all power sources for a minute.
5 Steps To Doing A Hard Reset
- Remove Power: If hardwired, flip the breaker at the electrical panel, and then disconnect the wiring harness at the back of unit. Open up the battery compartment and remove the batteries.
- Press Silence Button: After removing all power, press and hold the silence button for 10-20 seconds to actively drain any residual power.
- Wait 1-2 Minutes: Before restoring power, wait an additional 1-2 minutes to clear out any remaining charge.
- Reinstall: Install the CO alarm back onto the bracket with the battery, reconnect the wiring harness, and flip the breaker.
- Test: Hit the test button to make sure the alarm is working.
Fix #5. Relocate It
A carbon monoxide alarm may emit nuisance chirps if it is installed too close to gas appliances, the kitchen, or bathrooms.
Circuitry in the alarm can signal interference and it will start chirping or beeping — usually 1-5 beeps per minute. CO alarm chirps are typically caused by a low battery or end-of-life signals so verify that it isn’t those issues before relocation.
Here are some guidelines to follow:
- Fuel-burning appliances (furnace, water heater, stove): At least 15 feet away.
- Kitchens or areas with cooking fumes: At least 10–15 feet away.
- Bathrooms or areas with high humidity/steam: At least 10 feet away.
- Air vents, fans, or HVAC returns: At least 3–5 feet away.
- Windows or doors with direct drafts: At least 3 feet away.
- Direct sunlight or heat sources (lamps, heaters): Keep at least 3 feet away.
I recommend doing a hard reset first if you don’t see an obvious environmental reason prior to relocation.
Ideally, you want to have at least one CO detector on each home level and near any bedrooms. The best spot is in a central location and putting it at least 5-6 feet above the floor.
3 Steps to CO Alarm Relocation
- Identify Interference: Try to determine if the CO alarm is too close to an HVAC vent, gas appliance, the kitchen, or bathrooms.
- Choose New Location: Pick a central location, at least 5-6 feet above the floor, and near living spaces (bedrooms, living room, dining room). Give proper clearance away from the kitchen, bathrooms, or appliances.
- Test After Install: After the install in the new location, hit the test button to verify that the CO alarm is still working.
How To Test A Carbon Monoxide Alarm (Accurate Testing)
Homeowners can use commercially available aerosol CO spray cans to safely simulate a real carbon monoxide alarm.
It’s essential not to confuse CO spray cans with smoke/fire testers. Smoke can testers contain particles that simulate smoke from fires. CO testers contain chemicals that releases carbon monoxide (or mimics CO gas) which gives off a controlled low-level burst.
You simply spray a short burst of the CO gas onto the tester to see if it triggers an alarm.
The downside of hitting the test/silence button on a CO detector is that it doesn’t actually simulate a real-world situation of carbon monoxide gas.
4 Steps To Using A CO Test Can
- Position Can: Follow the instructions on the can, but typically you will need to spray the can several inches to a foot away from the CO detector.
- Spray: Press the can for a short burst of CO gas directly on the CO alarm vent hole.
- Observe: The CO alarm should start alarming within a few seconds.
- Turn Off Alarm: You can turn off the alarm by pressing the silence button or waving a magazine over the detector to remove gas from inside the unit.
Final Thoughts
A beeping carbon monoxide alarm may be annoying, but it’s an essential part of home safety.
Whether the sound signals a low battery, a dirty sensor, a faulty appliance, or an actual CO emergency, understanding the different alerts can give peace of mind.
Leave a comment below if you have had a recent experience with beeping CO alarms or if you want to ask me a question!