Device sends %CO2% instead of the actual value

[joshi04]

I'd just like to add, that mine two sensors also stops sending data after about ¾ of a day.
From the other thread I've limited the voltage of the power supply already being below 5,25V without change of behavior.
As far as I can remember somewhen in the past the sensors worked properly without interruption. Unfortunately and for sure I did not note the date or firmware version for which it worked well. 
Therefore currently just following this thread also, hoping for a solution and avoiding to update to the recent firmware.