Kidde 900-0235: lights, beeps & chirps explained
Plug-in CO alarm with 9V battery backup. Here is what every light and sound on the Kidde 900-0235 means, how to test and hush it, and when it needs replacing. I install this model across Vancouver and the Lower Mainland. For carbon monoxide protection, see our carbon monoxide alarm installation.
What the lights mean
| Light | Meaning |
|---|---|
| Green, steady | Plugged in and working. Normal. |
| Green, flashes about every 10 s | Running on the 9V backup battery (no power at the outlet). |
| Red, flashing with 4 beeps | CARBON MONOXIDE detected. |
| Red flash + 1 beep every 15 s | Low or missing 9V battery. Replace it. |
| Red flash + 1 beep every 30 s | Error: the alarm needs service or replacing. |
What the beeps and chirps mean
| Sound | Meaning |
|---|---|
| 4 quick beeps, 5 s pause, repeat | CARBON MONOXIDE. Get everyone into fresh air and call 911. |
| 1 beep every 15 s | Low or missing 9V battery. |
| 1 beep every 30 s | Error. Replace the alarm. |
| Chirp every 30 to 45 s, test button does nothing | End of life or failed sensor. A new battery won't fix it. Replace the alarm. |
Want to hear them? The free app's sound library plays each pattern.
How to
Test it
Press the Test/Reset button. It sounds 4 beeps and stops.
Silence an alarm
Press Test/Reset. If CO is still present, it will sound again. Don't ignore it: get into fresh air.
After a power outage
It runs on the 9V battery and the green light flashes. When power returns, the light goes steady.
Life: Kidde has listed both 7 and 10 years for this model over the years. Use the date on the label, and if it's 7+ years old, plan to replace it. A new battery does not stop an end-of-life chirp.
How long does it last?
Replace it 7 years after the date printed on the back. The test button can still work after the sensor has worn out, so the date is what counts. Sometimes the date is on the side, but the back is the best place to look. Need one swapped? See smoke alarm replacement and repair.
Price
$49.99 installed, plus the flat $99.99 service fee. GST only. See all prices.
Source: manufacturer's manual. Always follow the instructions that came with your alarm.
Other alarm guides
Kidde 30CUA10-VCA · Kidde 30CUD10-CA · Kidde 20SA10-CA · Kidde 20SD10-CA · Kidde i12010S · Kidde i12010SCO · Kidde i12040ACA · Kidde 900-0220CA · Kidde P4010ACS
All alarm guides · Chirp codes: Kidde vs First Alert · Kidde smoke alarms in Vancouver