Carbon Monoxide Detector Lights
CO Detector End-of-Life Light: What It Means and What To Do
Quick answer: A CO detector end-of-life light means the alarm has reached the end of its sensor life and should be replaced, not ignored.
What this light usually means
A CO detector end-of-life light means the alarm has reached the end of its sensor life and should be replaced, not ignored. The exact meaning can depend on the device model, the label beside the light, and whether the light is solid, blinking, flashing, pulsing, or alternating with another color.
Common causes
- CO sensor has expired
- Alarm reached rated service life
- End-of-life warning chirp or light
- Device can no longer reliably detect CO
- Model-specific replacement signal
What to check first
- Check the printed manufacture or replace-by date.
- Check the model manual for end-of-life signals.
- Replace the entire alarm if it is at end of life.
- Do not remove batteries to silence an end-of-life warning unless replacing the unit.
- Install the replacement according to the manual.
Important warning
A CO alarm at end of life may not protect you. Replace it promptly.
When it may be normal
This light may be normal if the device recently powered on, is pairing, is charging, is updating, is connecting, or is completing a setup step. If the light changes after a few minutes and the device works normally, it may not require further action.
When to contact support
Contact the manufacturer or a qualified professional if the light stays on after basic checks, appears with warning sounds, appears with heat or burning smells, affects a safety device, or comes back repeatedly after restarting.
Official sources
Use these official support resources to confirm the exact meaning for your model:
Related light guides
Carbon Monoxide Detector Red Light
A red light on a carbon monoxide detector can indicate alarm, fault, memory, low battery, or end-of-life depending on the model. Treat any CO alarm as serious.
Carbon Monoxide Detector Lights · General
CO Detector Green Light
A green light on a carbon monoxide detector usually means the alarm has power or is operating normally, depending on the model.
Carbon Monoxide Detector Lights · General
FAQ
What does a yellow, amber, red, or display indicator model-specific light usually mean?
A CO detector end-of-life light means the alarm has reached the end of its sensor life and should be replaced, not ignored.
Should I reset the device right away?
Usually no. Start with simple checks such as waiting, checking power, checking cables, restarting normally, and reading the official manual before doing a factory reset.
Does the exact model matter?
Yes. Brands often use the same light color for different meanings across different models, so always confirm with the official manual or support page for your exact device.
Last reviewed: 2026-05-05. General information only. Always follow the official manual for your exact model.