Comparing the datasheets for the PASCO2V01 and the new PASCO2V15 the old one actually seems a little better as far as CO2 measuring performance goes. They are the same on most things, but the old one has slightly better accuracy.
The new one is ±(50 ppm + 5%) between 400 ppm and 3000 ppm.
The old one is ±(30 ppm + 3%) between 400 ppm and 5000 ppm.
The big difference is this:
> Infineon has recently introduced the PASCO2V15, a new 5 V sensor to improve air quality monitoring in building environments.
Both of them require a dual voltage power supply. They both want 3.3 V for their digital components and a higher voltage for their IR emitter.
For the older one that higher voltage is 12 V. For the newer it is 5 V.
Small CO2 sensors have been available for years, for about $50. Compare [1].
Life of this new device is only 10 years, which is short for HVAC systems. A hotel might have a thousand of these. Older devices say "15+" years.
All these devices have a calibration problem. They drift. They try to correct by treating the lowest value they ever see as "normal" (that's about 400 ppm CO2 today, vs 300 PPM in 1950) and recalibrating. So they're not useful for observing a general increase in CO2. They're also not useful for greenhouses, where CO2 levels may drop below ambient CO2 due to photosynthesis. Manual recalibration is possible but requires feeding in pure nitrogen and a known nitrogen/CO2 mixture.[2]
Devices which don't need that re-calibration exist.[3] They're more complicated. Also don't seem to be stocked by the usual distributors.
[1] https://rmtplusstoragesenseair.blob.core.windows.net/docs/pu...
[2] https://www.co2meter.com/blogs/news/7512282-co2-sensor-calib...
[3] https://www.murata.com/en-us/products/sensor/co2/overview/te...
Murata announced this in 2019, and there's a part number (IMG-CA0011-00/ IMG-CA0012-00/IMG-CA0023-00) and a full data sheet.[1] But no distributor has it. Not DigiKey, Mouser, Arrow, or Newark. Even Octopart doesn't list it. It's on Murata's list of recommended products, not the discontinued list. Try contacting Murata.
[1] https://go.murata.com/rs/382-MEZ-125/images/HC%20CO2-sensor%...
Chinese fabs are notorious for running secret shifts that make their customers’ chips to sell themselves. They’re the exact same chip but made without authorization, using the customer’s exact design.
That said, Sensirion has their own CMOS fabs in Switzerland so that’s very unlikely to be the case here. If they work at all, the counterfeit chips are probably some Chinese CO2 sensor IC that's small enough to fit into the same package, lightly customized to fit the pinout of the original. Or it's just a microcontroller inside faking it a la FTDI.
So many of those actually measure humidity, temp and VOCs and try to derive some sort of CO2 reading out of those.