How to reset an X-Sense smoke detector
Quick Answer: First make sure there is no fire. Then check what it is doing: a single chirp every 30 to 60 seconds is a low battery or end of life, while a loud repeating alarm means it has detected something. To reset a battery unit, remove it from the bracket, take the battery out, hold the test or silence button for about 20 seconds, then refit a fresh battery. For a hardwired unit, switch the breaker off first and do the same with the backup battery.
Before anything else. If the alarm is sounding continuously, treat it as real until you have checked. Get everyone out, then look for fire. A false alarm costs you five minutes. Assuming a real one is false costs more than that.
If your unit is a combination smoke and carbon monoxide alarm, which several X-Sense models are, the CO half is not something to reset and investigate later. Skip to what to do if it is the CO alarm.
Chirping or alarming? They mean different things
| What you hear | What it means | What to do |
|---|---|---|
| One chirp every 30 to 60 seconds | Low battery, or the unit has reached end of life | Replace the battery. If it keeps chirping on a fresh one, check the date on the back |
| Loud repeating alarm | It has detected smoke or CO | Get out, check for fire, call for help. Do not start with the reset |
| Chirp with a different pattern or a spoken warning | Often a fault code or a CO warning on combination units | Check the manual for your model. Patterns differ between smoke and CO |
| Alarm that stops and starts with cooking or showers | Nuisance alarm from steam or cooking aerosols | Ventilate, then consider relocating the unit |
Almost everyone searching for how to reset one of these has a chirp, not an alarm. A chirp is the unit asking for a battery or telling you it is finished. Resetting it clears the noise for a while and does not address either.
Resetting a battery-powered X-Sense alarm
- Twist or pull the alarm off its mounting bracket.
- Remove the battery.
- Press and hold the test or silence button for about 20 seconds to drain the residual charge.
- Fit a fresh battery, the right way round, and refit the alarm to the bracket.
- Press test. You should get a loud alarm. If you do not, the unit is faulty and needs replacing.
On sealed ten-year models such as the SC07-W there is no removable battery, so there is no battery reset. When one of those chirps for end of life, the unit is replaced. Our X-Sense SC07-W review covers that model.
Resetting a hardwired X-Sense alarm
- Switch the circuit breaker off for the smoke alarm circuit. Off, not on.
- Take the alarm off its bracket and unplug the harness connector.
- Remove the backup battery.
- Press and hold the test button for about 20 seconds.
- Refit the battery, reconnect the harness, remount the alarm, then switch the breaker back on.
- Press test to confirm it sounds.
Interconnected alarms are worth knowing about here: if yours are wired together, one unit in alarm sets off all of them, and the one chirping is not always the one with the problem. Work along them until you find the unit that is actually due.
If it is the carbon monoxide alarm
Do not reset it. Do not silence it and wait. Carbon monoxide has no smell and the alarm is the only warning you get.
The EPA's guidance is unambiguous: get everyone out of the house immediately and seek medical attention, and "don't ignore symptoms, particularly if more than one person is feeling them. You could lose consciousness and die if you do nothing." Its full advice is on the EPA carbon monoxide page.
The symptoms to watch for, per the CDC, are headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion. They are easy to mistake for flu, which is exactly what makes CO dangerous. Tell the doctor you suspect CO poisoning, because that changes what they look for.
Call the fire department or emergency services from outside, not from indoors, and do not go back in until they say it is safe.
Why it keeps false-alarming
- Dust. The sensing chamber fills over time. Vacuum the outside of the unit with a soft brush attachment every few months.
- Steam and cooking. Bathroom and kitchen aerosols read as smoke. Relocating the alarm is the fix, not silencing it repeatedly. X-Sense publishes placement guidance.
- Airflow. Mounted next to a supply vent or a draughty spot, an alarm sees more dust and more temperature swing than it should.
- Insects. Small insects getting into the chamber is a genuine and under-recognised cause.
- Humidity. Very damp air can trigger some sensors, which is one reason alarms do not belong directly outside a bathroom door.
When to replace rather than reset
The US Fire Administration is specific: "Replace the entire smoke alarm every 10 years", test it monthly, and on units with a replaceable battery "replace the batteries at least once every year". Their full guidance is on the USFA smoke alarm page.
Ten years runs from the manufacture date printed on the back of the unit, not from when you installed it. Take it off the bracket and look. An alarm that chirps on a brand new battery, fails a test, or is past its date is telling you it is done.
The old version of this page suggested replacing batteries every two years and gave a lifespan of 8 to 12 years. Both were wrong in the direction that leaves you less protected. Annually, and ten years.
What not to do
Do not remove the battery to stop the noise and leave it out. A disabled alarm is the most common thing found in homes after a fatal fire. If a unit is nuisance-alarming badly enough that you are tempted, move it or replace it the same day.
Do not paint over an alarm, and do not cover it while cooking and forget about it.
Frequently asked questions
How do I stop my X-Sense smoke detector chirping?
Fit a fresh battery. If it still chirps, check the manufacture date on the back. A unit past ten years chirps for end of life and no battery will stop it.
Why does it chirp after I changed the battery?
Either the residual charge has not cleared, so hold the test button for 20 seconds with the battery out, or the unit has reached end of life, or another interconnected alarm in the house is the one chirping.
How do I silence an X-Sense alarm while cooking?
Press the silence button once. It hushes for several minutes and then re-arms itself. Ventilate the room while it is silenced, and never disable the unit instead.
How often should I test it?
Monthly, per USFA guidance. It takes a few seconds and it is the only way to know the sounder still works.
How long do X-Sense smoke detectors last?
Ten years from the manufacture date on the back, in line with the guidance for smoke alarms generally. Sealed battery models are designed to be replaced whole at that point.
What is the difference between the smoke and CO alarm patterns?
They differ by model, and the manual states both. It matters: a smoke alarm means find the fire, a CO alarm means leave the building. Learn yours before you need it.
Can I reset a sealed battery X-Sense alarm?
There is no battery to pull, so there is no battery reset. If a sealed unit is chirping for end of life, replace it.
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