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CO Detector Expiration Calculator

Most CO detectors expire silently — the battery still works but the sensor can no longer detect carbon monoxide. Enter your purchase year to find out if you're still protected.

⚠️ Quick check: Find the manufacture date on the back of your detector. If it was purchased or manufactured more than 7 years ago (or more than 10 years ago for AirShield), your sensor has likely degraded and should be replaced — regardless of whether it still makes noise.

CO Detector Lifespan by Status

Age Status What It Means Action
0–2 yearsExcellentSensor at full sensitivitySet a reminder for year 5–7
3–5 yearsGoodWithin expected sensor lifePlan replacement in 1–2 years
6 yearsExpiring SoonNearing end of sensor lifeUpgrade now
7+ years (most brands)ExpiredSensor degraded — may not alarmReplace immediately
10+ years (AirShield)ExpiredExtended lifespan reachedReplace immediately

Why CO Detectors Have an Expiration Date

Unlike smoke detectors, which use optical or ionization chambers that stay stable for years, CO detectors use an electrochemical sensor — a small chemical cell that reacts to CO molecules. Over time, that cell dries out, gets contaminated, and loses sensitivity.

The result: a 9-year-old detector might still chirp when the battery is low, but its sensor may no longer trigger at 70 ppm — the concentration that causes headaches — or even at 150 ppm, which causes incapacitation within 2 hours. You would have no warning.

5–7 years
Typical lifespan
Most brands on the market
10 years
AirShield lifespan
Extended electrochemical sensor
No alarm
Risk when expired
Sensor too degraded to detect CO

Frequently Asked Questions

How long do CO detectors last?
Most CO detectors last 5–7 years. The electrochemical sensor that detects carbon monoxide gradually loses sensitivity over time, regardless of whether the battery is fresh. AirShield uses a 10-year electrochemical sensor — the longest standard lifespan available.
Does my CO detector expire even if it still beeps?
Yes. The low-battery chirp is a separate circuit from the CO sensor. A detector can make noise while its electrochemical cell is too degraded to detect CO at dangerous levels.
How do I find out when my detector was made?
Check the back or bottom of the unit — manufacturers are required to print the manufacture date. If the label is missing or unreadable, replace the detector.
What happens if CO is present and my detector is expired?
An expired detector may fail to alarm, alarm late, or alarm at much higher concentrations than safe limits. This is why replacement timing matters — it's not hypothetical risk.

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10-Year Sensor Life

Stop Replacing Every 5 Years

AirShield's electrochemical sensor lasts 10 years — twice as long as most. Real-time OLED PPM display. UL 2034 certified. One-time plug-in, decade of protection.

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