P2681 on my 35d. Need help

[x5wntd]

Hey all. I have '15 f15 35d 90k miles
I have P2681 showed up last winter.
Just replaced thermostat and water pump , still having that code coming back.
Thinking of a coolant sensor. (A) (B) way too different.. why?
Some resources referring this code to the coolant bypass valve itself
Third are "The passenger compartment heater coolant control valve regulates the engine coolant flow into the cabin heater loop depending on engine coolant temperature and ambient temperature conditions. "

Any thoughts? Thanks in advance

[x5wntd]

Bimmerlink