Fit the v9 sensors and close the enclosure
8 steps
Confirm the PCB revision
Read the PCB version beneath the AirGradient logo. Keep power disconnected while fitting modules; select a different upstream guide if the board is not the documented v9 design.
Check: The physical revision matches the instructions.
Companion guide, source references and reuse license
Install the temperature/humidity module
Identify the SHT4x module, distinguish it from the similar SGP41, and insert it in the bottom-left socket labeled SHT1 with the AirGradient logo facing outward.
Check: The SHT module is in SHT1 and its pins are seated evenly.
Seat the CO2 module
Fit the Senseair S8 or S88 in the sockets labeled CO2 Sensor. Align every pin with its socket before pressing the module home.
Check: No pin is outside a socket or bent beneath the module.
Install the VOC/NOx module
Place the SGP41 in the top-left slot labeled I2C3. Orient the sensor outward as in the build-guide illustration.
Check: SHT4x and SGP41 have not been swapped.
Record the PM serial identifier
Read the label on the blue PM module and record its serial number, including the first eight digits used by the project batch-correction guidance.
Check: The identifier can be retrieved later without reopening the case.
Test the assembled board
Connect the 5 V, 2 A USB supply and confirm the display starts. Complete the chosen Wi-Fi onboarding workflow if network use is required.
Check: The screen starts without repeated resets or missing-sensor symptoms.
Close the enclosure
Disconnect power before handling the assembly. Seat the PCB in the enclosure, then close it with the four supplied screws through the documented rear ventilation positions.
Check: The case holds the board without forced screws or obstructed vents.
Check the finished monitor
Reconnect power and confirm normal startup. Record the assembly date; do not treat a newly powered CO2 sensor as already stabilized by its automatic baseline process.
Check: The enclosed monitor operates and its vents remain clear.
Project credit: AirGradient and open hardware contributors. Guide reuse: CC-BY-SA-4.0. Upstream reference. Prepared with AI assistance for a TwinWorks-managed contributor; no physical build/test is claimed.