S8 CO2 reading permanently changed to -3 (Pro, Pre-soldered, PCB v 4.2)


My pre-soldered AirGradient DIY Pro (PCB v 4.2) has been working fine for several months, but, a couple of weeks ago, the CO2 reading changed to -3 and stayed like that ever since. No particular external event seemed to have caused this change; I simply checked the display at some point and the CO2 reading was -3.

Following the information in this thread Co2 reading of -3 constantly, I updated the AirGradient firmware to the latest version, but this did not resolve the issue.

The board itself was pre-soldered, and it was working completely fine for the first several months. Is it possible that a faulty S8 CO2 itself is the root cause here? Here is a picture of the current state of the board.

We have extremely few S8 breaking.
Does the sensor module still blink every few seconds with a yellow light?
Can you check if it gets power?

Yes, the sensor module still blinks every few seconds with a yellow light, so it is still powered.

I don’t have access to a multimeter at this time, so I won’t be able to check the individual connections, unfortunately.

Can you reflow the solder points with a soldering iron:

If that does not work please contact our support through our website form.

I have to admit that I am by no means well-versed in soldering (hence my purchase of the pre-soldered product), nor do I have access to a soldering iron at this time. I can try to get hold of one and get back to you if reflowing the connections fixes the issue.