BME Troubleshooting (temperature, humidity, pressure, and VOCs)

This article will walk you through troubleshooting steps for your device’s BME sensor. The BME measures temperature, humidity, and pressure. Some BME sensors also measure VOCs.

Raw temperature and humidity readings can be different from ambient conditions due to heat produced by the device. The PurpleAir map provides data layers with corrections that attempt to match ambient measurements.

You can tell that the BME in your PurpleAir device is malfunctioning if the temperature, humidity, and pressure readings are extremely inaccurate. The device may also detect something wrong with the BME and stop reading from it. If this happens, it will be indicated on the map with an error message. An example is pictured below.

An image of an error message saying "Temperature, humidity and pressure sensor is not detected."

You can try the following steps to correct a faulty BME sensor:

Power Cycle the Device

Sometimes power cycling the device is all that’s needed. Unplug the device to power it off. Wait at least 30 seconds before plugging it back in.

Unplug the BME sensor board, and plug it back in

The device should be powered off for this step

If power cycling the device did not work, try unplugging the BME sensor board and plugging it back in. Look at the replacement videos below for instructions on removing and re-inserting the BME sensor board.

This step is especially important if you have replaced the laser counters recently. The BME sensor board can sometimes be jostled out of place when replacing other internal components.

Replace the BME

If the device is still functioning but the BME isn’t, a replacement will be needed. These are currently not available for purchase on the PurpleAir website, so send a request to for a quote.

Replacing the BME for the PurpleAir Flex and Zen
Replacing the BME for the PurpleAir Classic and Classic-SD

Learn More

Learn how to troubleshoot power related issues .
Learn more about SD Card Logging and Troubleshooting .
Learn more about what PurpleAir sensors measure and how they work .