AirGradient OneV9 Indoor - 0 for all PM readings

I have recently purchased the Outdoor monitor and decided to pick up the indoor pre-soldered unit.
I am not getting any PM readings 0.3, 1, 2.5 or 10. See the logs here.

I upgraded to the latest firmware 3.0.9 in attempt to fix the issue, reseated the cable between the sensor and the board, but I am still getting no readings.
I will reply with a photo of my board for reference.
Not sure what to do next.

Here is the board view

Could you take the pm sensor from your outdoor kit and connect it to the indoor board (using the indoor pm cable) and see if it works then?
Also please send the serial number of the pm sensor that seems to not work.

I swapped the PM sensor from the outdoor kit and it seems to have worked initially for the first 5 minutes. I was getting readings, but they seemed low. After 5 minutes all but the PM 0.3 sensor went to 0 and stayed there. Log file is included.

I did try the indoor PM sensor on the outdoor board and the sensor is returning normal readings for all PM levels for this environment. I don’t think it is the sensor that is defective.

See my next message, all readings dropped to zero after several minutes.

Scratch that, the indoor sensor on the outdoor board, all readings dropped to zero.
Here is the serial number of the indoor PM sensor.

And now the Outdoor PM sensor back in the outdoor unit is not working correctly, only showing PM 0.3.
I am going to let it sit overnight and see if it recovers.

After leaving outdoor PM sensor in the outdoor unit overnight, the outdoor PM sensor is now dead as well .
The only readings I am getting from the PM sensor is the 0.3 count, which hovers around 60 (plus or minus 10 points). Now I have two dead sensors. I believe that the board for the indoor sensor is defective and it is effectively and efficiently killing the PM sensor.
What is my next step to resolve this issue?

Just want to let you know that we are looking into this.

One more thing. We currently have extremely low PM values across wide areas of the USA. Some even showing zero. So it also just might be the correct reading especially if you are in a clean air area (eg outside a large city etc)


My issue sounds very similar to this. 0 on all PMS readings.

I did “once” get a series of values on the 0.3um data, but that was only for 1 hour on 1 day. Anomaly?

Is it possible to provide a test firmware image so that we can flash the device, run a test on the PMS sensor using it and determine is the board/sensor/firmware/user is at fault?

I should probably also seek to install the stock firmware to keep Achim happy :slight_smile:

The other approach I am tempted to take is using the scope to capture and decode the UART comms with the sensor. For this I will have to solder “tags” onto the JST pins. So anything you can suggest before I get that serious?

Is there any merit in modifying the ESPHome PMSx003 driver to add more logging of the UART contents, frame errors, resets, payload lengths etc?

EDIT: “Hardware Unit tests” I call these. Firmware’s which do not make the device work, but simply test the hardware and show a green light. Maybe you already have, this is why I asked.

So the plot thickens.
I returned the outdoor PM sensor to the outdoor unit, reflashed to 3.0.9 with a reset and it is now back in operation, giving expected readings.
My indoor unit is still returning zero values for all but the PM 0.3 count.
I have reflashed with a reset and no change after 24 hours.
So, back to where I started.
I do like venquessa idea of utilizing a hardware test firmware, if one exists.
I reached out to Support but I am still waiting on a reply. Anything else I should consider?

We didn’t forget about you but are still investigating and discussing the best solutions. I like the idea with the test firmware but this could also be integrated into the normal one.

Do you have hepa filters in your house? I still wonder if you not just have excellent air quality in your home?
Can you bring the indoor monitor outdoors and see if the PM increases then to the outdoor level?

I have a secondary air quality monitor that is literally sitting right next to it. The readings from this monitor are pretty close to accurate, with current PM 2.5 values of 45 µg per cubic meter, while I am getting 0 on the AirGradient Indoor V9 sensor.
No hepa in that area of the house.

You can turn on an even more verbose logging for the PMS sensor only. Check out the Logging component for details.

I often get 0 in my home, but my Ikea pm2.5 sensor shows 10+ at the same time.
I trust the AirGradient

I took the outdoor AirGradient inside, placed it next to the Indoor unit and the outdoor is reading 28µg per cubic meter for PM 2.5 while the indoor unit is a solid zero. (this was after 3 hours)
I am not trusting the indoor unit at the moment.

Ok. Case clear now. We will send you a replacement. You will get a reply from the support ticket soon.

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I will check that out.

I smoke in the office 3 feet from the sensor. I also tested it with some burning cardboard, the same way you would tests a smoke alarm. It still read 0.

Just to clarify, are you on the AirGradient stock firmware or on ESPHome?

If on ESPHome, it would be good if you could repeat the smoke experiment with the stock firmware just to make sure it’s not an issue with ESPHome (which I don’t expect, but better be sure).