1D2008 code - map thermostat jammed open

[X5Nafta]

14 XDrive3.5i with 93k miles on it. Got check engine light and showing 1D2008 code in ISTA.

Code appears to be pointing to Auto Tranny cooler Thermostat stuck open, but based on some reading it could also be coolant thermostat (BTW WP and thermostat are original).

Anyone had experience with this code?

Thanks in Advance!

[X5Nafta]

UPDATE
Found TSB on line related to my DME error:

Fault Code 1D2008: Map thermostat: jammed open is stored in the DME. There may also be a complaint of low heat output with lower outside temperatures.

https://static.nhtsa.gov/odi/tsbs/20...58490-9052.pdf

According to tsb, by process of elimination, I had to find out if it was my engine coolant thermostat or ATF trans thermostat (they are in the same loop). Followed their procedure, and ended up being my engine thermostat.

ADDITIONAL SYMPTOMS:
* On 40-50 F deg days, my coolant temp was between 30-45 deg C.
* Radiator Fan was running at full blast.
* Otherwise, car drove normal.

I will be replacing WaterPump and Thermostat, since they are original and 93k miles old.