Sensor malfunction

Sensor is reading higher than surroundings sensors.

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So is mine. It spiked a few days ago and now just staying in a range around 55-70. I vacuumed it out but it didn’t help.

I tried the vacuum again but without the brush attachment. I held it on the bottom for 3 minutes and the problem went away.

Update: I put the sensor back outside and the problem came back. Replacing the USB cable resolved it!

There are multiple reasons why a sensor could be reading higher. The sensor may be experiencing a hyper-local event, causing its readings to be temporarily higher. Smoking and cooking are two common examples.

If the sensor’s readings are consistently high, you’ll first want to check its placement. Is there anything near the sensor that could be a consistent source of particulates? You can try moving it to a new location and see if the readings change.

If you’re confident the sensor placement isn’t the cause, you’ll want to try cleaning your sensor. Insects or debris can get inside the laser counters, causing readings to become high, and cleaning can sometimes resolve this. If cleaning doesn’t work, you can purchase replacement laser counters for your device.

Hi @MoldBoy, do the high readings return if you use the old USB cable again?

Yes. The old usb cable is a 50 ft long flat, very cheap from amazon. The 5w peower was also very cheap. Switching over to high quality cable and power is stable. I switched back to the old cable 4 times and immediately the seemingly random high readings returned.

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Thank you for the provided details. If the laser counters don’t receive enough power they can provide erroneous readings. This especially makes sense given the cheapness and length of your old USB cable.

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All was fine until the cold weather hit. I’ll have to assume it caused a voltage drop on the cheap cable. I wouldn’t recommend flat usb cables whatsoever though. Thanks for the info!

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My indoor sensor is reading low. Indoors it is almost always zero and, if I put it outdoors it reads about 10 points lower than surrounding sensors. I have tries cleaning the sensor with compressed air with no change. Do I need a new sensor or is there a possible other cause?

Hi @Dale

Please send an email to with the device ID of your sensor included. There could be a number of things going on, and we would like to look at it in our system.

Have an excellent rest of your day!

I’ve got a similar problem. I normally have the map set at >.3um / dL, and at that setting my sensor reads many times higher than nearby sensors. At the moment, it’s 48 times higher. But, when I set the map for AQI 2.5, it’s only twice as high. When set for >.3 um, it reads fairly constant, between about 500 and 800. I just blew into it trying to remove any foreign objects, and it went up to close to 4,000, so it seems to be responding. In the next sample it was back to it’s normal range

Another thing about it is that it always shows 100% comparison with the two internal sensors, but if I download some data, and compare them in an Excel file, they’re mismatched by an average of 32%.

Got any ideas on what might be wrong with it? Thank you.