What an annoying beeping and an inscrutable message. Our other alarms beep constantly which I just hate. But this little plug-in co2 system dumps this strange code L6.
It should be flashing alternately with the '0' with a short beep every 15 seconds. The indication is to replace the 9v battery.
And every 10 years you have to replace it and it will beep uncontrollably.
I had great hopes for a wifi connected first alert one link (but that did work 🙂 so here how to replace the batteries. You basically push open the slot and put a 9V in.
— Read on askinglot.com/what-is-code-l6-on-kidde-carbon-monoxide-detector