Interesting job in today B M W 7 Series 2002. The car was presented with passenger rear floor flooded.
The leak was traced to be coming in from behind the front glove box. After removal of the glove box, seat and carpets it was plain to see the water was coming in along with the wiring from the ECU storage box in the engine bay. After removal of ECUs and box, which had been partially submerged for some time, the drain beneath had been blocked with leaves and debris.
The drain which is in a very un accessible place was cleaned and modified so it would never block again. The DME ECU had some build up of verdigris on the multiplug and pins. This was treated with electrical cleaner and cleaned up well. The vehicle was re built and cleaned with lots of silicon sealer so the chances of a repeat were re removed.
Although a lengthy job, the outcome was very satisfying. If the owner had left it much longer before investigation he would be paying for 1 or 2 ECU units and lot heavier bill.