[lsh123]

I have a cheap (about $20-25 a couple years ago) sensor from Amazon in my plane. It calibrates itself when I turn it on and I check it works on the ground before every flight - open the window after starting the engine and see co2 going up ;) Granted, I don’t really care about any small errors or small changes - I want the sensors to warn me if co2 concentration goes up significantly (e.g. because of leaks from exhaust system).

[ericpauley]

Are you sure this isn’t a carbon monoxide (CO) sensor? While exhaust might increase CO2 as well, pilots are usually far more concerned about CO poisoning and usually use CO detectors.

[travisjungroth]

I've never heard of that. Do you have a CO sensor as well? Those are common, mostly in a very cheap one-time-use dot form.

[travisjungroth]

I should say "disposable" instead of "one time use". https://www.aircraftspruce.com/catalog/pspages/asaCO.php