The fault described is because NTC R2 is out of range or at fault, this is the one located on the heater box at the back.
Its resistance should be 25k ohm at 25’c
Check that its not all covered in crap too as thats quite common.
And the condensor at the front also gets blocked up with fluff and causes them to throw up some funny faults.
BSH Part number for the said NTC is 163297
Hope this helps! 😉