Temperature too high from indoor and outdoor units

[Daniel1]

I bought two AirGradient indoor (I-9PSL-DE) and one outdoor (O-PST) units. They all give temperature readings that are too high. I have six aqara temperature sensors, an Aranet 4 and a UHoo. I put them all on a table with the air gradient sensors to check calibration. The others agree within 0.6F. The indoor AGs are 2F and 2.6F too high consistently throughout the day. Both too high and 0.6F from each other. The outdoor is about 6.5F high.

I initially set them up in Home Assistant. I saw the other forum post about setting configuration source to cloud; changing that did not change the numbers. I since added them to app.airgradient and see the same numbers there.

I turned the outdoor unit off for 20 minutes, then powered it on and the temperature came on low and then rose back up over about 15 mins.

All three say their firmware is up to date.

Is there a fix or additional debugging I should provide? Thanks.

[Altair_AirGradient]

For the outdoor unit, the higher temperature readings are due to the sensor being inside the casing and thus there not being enough airflow like the natural convection in the indoor units. The standard calibration for the outdoors applies an offset to account for this which I think is very close to the difference you’re seeing. Could you try applying the calibration formula again?

The indoor units, however, are normally be very accurate so this is unusual. I’ve seen them compared them to a reference instrument and be within 0.1 Celsius.

Could you confirm whether the units are upright (not on their side) and whether these were purchased pre-assembled or as DIY kits?