OK, so in order to do this, I think we need to first configure your Egg so that it is able to report negative concentration values so that we can adjust your SO2 calibration as well, and we can let it run overnight in that mode to collect some data to inform our adjustment. The commands you should run from Config Mode in a serial terminal are:
so2_negz 0
o3_negz 0
exit
Then wait for your Egg to connect to the network and print out the message “Info: Writing mirrored config...OK”. Then plug it in as you normally would and let it run overnight, I’ll take a look at the readings in the morning, and then give you some more commands to run to alter the baseline voltage characterization tables.
Alternatively, if you want to send the Egg back to us, we can try and run it through another calibration cycle in our facility. Contact support at wickeddevice dot com if you want to go that route instead and we’ll work out details offline.