I found a
site that lists the Pxxxx codes for BMW...
P1835 Pressure Control Solenoid 'E' Circuit High
This would indicate what has already been suggested is correct - the circuit to the trans. mechatronic is faulty (or the mechatronic itself is faulty), with an open circuit connection (is that an oxymoron!?

) to the E circuit pressure control solenoid.
Time to give that connector a jolly good clean!
The connector in question is called X8505 and it's location varies a little, depending on which transmission you have...