Getting wrong temperature on MH-z19c

[vignesh8458]

Hi,

I am usning MH-Z19c sensor on esp8266.

I am getting the same temperature value:

CO2: 672
Temperature: -40
Accuracy: 0
CO2: 675
Temperature: -40
Accuracy: 0
CO2: 682
Temperature: -40
Accuracy: 0
CO2: 684
Temperature: -40
Accuracy: 0
CO2: 689
Temperature: -40
Accuracy: 0
CO2: 691
Temperature: -40
Accuracy: 0
CO2: 693
Temperature: -40
Accuracy: 0

Please help me on this.

[WifWaf]

This is due to the newer version of the sensor, the manufacturer shuffles the registries around and I'm currently not sure the best way to go about fixing these types of unpredictable changes.

I would like to have a fix in place soon, but I can't make any promises right now.

[vignesh8458]

Thanks for the reply.

I will wait.

[Cybolord]

me too; thank you in advance for your effort!

[etodorovich]

Me too, and thank you!

[WifWaf]

This should have been fixed in 04a6f85.

I'll add a new release shortly.

I only have two sensors to test the changes on, so hoping I'm correct in that it fixes all sensor versions over 5.00. If not, the firmware version (which can be found in the get device info example) would be helpful.

[Dixhom]

I have a similar issue with MH-Z19

CO2 (ppm): 0
!Error: Timed out waiting for response
Temperature (C): -17

The product is this.
https://www.aliexpress.com/item/32706795833.html
(the silver one on the leftmost pic)

[WifWaf]

I have a similar issue with MH-Z19

CO2 (ppm): 0 !Error: Timed out waiting for response Temperature (C): -17

The product is this. https://www.aliexpress.com/item/32706795833.html (the silver one on the leftmost pic)

I've not seen the silver version before, so it might be running significantly different firmware. Try using getCO2(false) as this uses the most documented command.