How to Test Your Smoke and CO Detectors (And When to Replace Them)

Somewhere on your ceiling right now, there's a detector that hasn't been touched since the day it was installed. It looks exactly like a working smoke or carbon monoxide alarm — but if you haven't tested it recently, you genuinely don't know if it is one. This is one of the most deferred safety tasks we see in homes across Del Sur, Carmel Valley, and Rancho Peñasquitos (92127, 92130, 92129) — not because families don't care, but because detectors are easy to forget when nothing seems wrong.

The problem is, a dead or expired detector offers zero protection. And it looks identical to a functioning one.

Why This Matters More Than Most Home Tasks

Smoke and carbon monoxide alarms are your family's first warning system. A working smoke detector gives you roughly three times longer to escape a house fire compared to no detector at all. CO detectors, meanwhile, guard against a gas that's colorless and odorless — you cannot detect a carbon monoxide leak without one.

Here's what most homeowners don't know: these devices have hard expiration dates. Smoke detectors are rated for 10 years from the manufacture date. CO detectors wear out even faster — most are rated for 5 to 7 years. After that, the sensors degrade and may not trigger reliably, no matter how many times you press the test button. The test button only checks the alert circuitry — not the actual sensing element.

If you moved into your home more than five years ago and haven't replaced your CO detectors, there's a real chance some of them are past their useful life right now.

How to Test Your Smoke and CO Detectors: A Quick Checklist

1. Find every detector in your home. Check all bedrooms, hallways, the kitchen, garage, and any room with a gas appliance. California code requires a smoke detector inside every sleeping room, outside each sleeping area, and on every level of the home. CO detectors are required on each level and near sleeping areas. Many homes, especially those in 92128 and 92131, were built before updated code requirements — so your coverage may have gaps.
2. Press and hold the test button on each unit. A working detector will sound a loud alarm. If you get a weak chirp, a brief tone, or no response at all, replace it immediately. Don't assume a faint alarm means it would still work in an emergency.
3. Check the manufacture date. Flip the detector off the ceiling mount and look at the back or inside the battery compartment. You'll find a printed manufacture date. If it's more than 10 years old (smoke) or more than 5–7 years old (CO), it needs to go — regardless of whether it passed the button test.
4. Inspect and replace batteries. For battery-powered units, swap in fresh batteries at least once a year. A good habit: do it when the clocks change. Sealed 10-year battery models are worth the upgrade — one less thing to track.
5. Clean the unit gently. Dust buildup inside the detector can reduce sensitivity or trigger false alarms. Use a vacuum with a soft brush attachment to clean the vents on the outside of each unit twice a year.
6. Note which detectors are combination units. Many newer homes use combo smoke/CO detectors. If you're replacing one, confirm whether it's a combo unit or a dedicated device — the replacement needs to match the function.
7. Replace any detector that's responded to a real event. If a unit has activated from actual smoke or CO exposure — not just a cooking incident — swap it out. Sensors can be partially depleted by a real exposure event and may perform less reliably afterward.

A Five-Minute Check That's Worth Doing Tonight

Grab a step stool, go room to room, and run through steps 1 through 3. It takes less than five minutes, requires no tools, and gives you actual confirmation of whether your family is protected — not just the assumption that they are. Pay close attention to the manufacture dates. Most homeowners are genuinely surprised to find detectors that are 8, 10, or even 12 years old still mounted to the ceiling.

If any unit is past its expiration window or failing the button test, replace it before the week is out. Detectors are inexpensive — most quality smoke/CO combos run $25–$40 at any hardware store.

Let Our Team Stay on Top of It

For Livd members, detector testing and replacement tracking is exactly the kind of task our team keeps an eye on. During visits, we note the age of your detectors, flag units approaching expiration, and replace them when the time comes — so you never have to wonder whether your home is covered.

We track it so you don't have to. That's the whole idea.

Already a Livd member? Add "smoke and CO detector check" to your task list in the Livd app and we'll take care of it on your next visit — including checking manufacture dates and flagging anything that needs replacing.

Not a Livd member yet? This is one of dozens of safety and maintenance tasks that's easy to defer and important not to. A Livd subscription means someone's actually tracking these things for your specific home — and handling them before they become a problem. Book your free home walkthrough at livdhomes.com and we'll build you a personalized maintenance plan to get started.