Sounds like an issue with the ambient temperature sensor circuit. This can cause a huge offset in the measurements. If an FFC flag is in use the ambient/chassis temperature measurement error will be transferred to the FFC calibration, so causing the offset in readings. The ambient temperature sensor can be as simple as a biased diode feeding an ADC input or it can be more complex, such as a self contained temperature sensor with I2C output. I do not know the type of environmental temperature sensor used in the Boson design but it is likely known from information on the internet.