MH-Z19B measures well the first 15 minutes, then 0 ppm about mh-z19 HOT 5 CLOSED

Have you tried manually calibrating the sensor? It might be due to the sensor lacking any reference values.

Outside of this, the only time it's happened to me is when I corrupted the firmware, but it took quite some effort.

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The sensor is calibrated. In fact, for the first few minutes it works perfectly, but then it dies (the light keeps flashing but it sends 0ppm).

There are 3 sensors. Maybe they are defective?

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I have a 4th sensor model MH-Z19C with the same code and works perfectly all the time (15 days)

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Is the issue with all 3 sensors?

If the library filter is on, it might be worth turning it off and seeing if it zeros or just erroneous data.

As a last resort, you could try setting the range to 2000 (if that's the CO2 limit you using), although it might make things worse. I can't remember the reason, however, I've had to do with this with a sensor before. Unfortunately, it's been a while since I used the sensor.

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Closing for now due inactivity, feel free to reopen.

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