I purchased a soldered unit and the CO2 monitor seems defective and I can't trust the readings. Sometimes it reports 0 if left on for extended periods, other t

I purchased a soldered unit and the CO2 monitor seems defective and I can't trust the readings. Sometimes it reports 0 if left on for extended periods, other times the readings are wildly out of range of what the module is listed to support. I have emailed them regarding a different issue and didn't have the best response back and hasn't inspired confidence to raise this one. On the plus side the module is replaceable and I'll probably just source it myself rather go through support.