PGlaves
#13338
Maybe the ECU is completely waterproof but I'm guessing there's a lot of things on the bike that can not take being under water for two days.
For what it is worth, the LJetronic ECUs on classic K75 and K100 bikes are not waterproof. I had one get wet once. I swapped in a spare, and after about a year with it sitting on a shelf I reinstalled the previously wet one and it worked fine.