The water issue is deadly, but the codes indicate that you could very easily have a conductor plate problem. They conductor plate is basically the internal wiring harness of the transmission. It also has the turbine speed sensors built into it.
It is rather cheap and accessible without removing the trans. Unfortunately if the water has delaminated the clutch material which is typical then you are still up for a rebuild.
If that is the case you should deal with it sooner than later if you have a competent local rebuilder. There are a number of improvements you would get by buying a rebuilt from MB:
VB, bearings between the internal shafts instead of bushings, but the units we have rebuilt have had no problem if the bushings were intact and were less than half of MB price. If you take the thing to meltdown you won't have a choice.