I found a slow drip coming from the water inlet valve. This was the source of the E-15 message. The water collected around the styrofoam disk, which then tripped the leak sensor. It was easy to replace the valve, following the video instructions.
At the same time, I decided to replace the two door seals, due to periodic leaking in the front of the dishwasher. The lower door seal replacement procedure was long, but the video was very helpful and thorough. The larger, upper door seal was very quick to replace, but there was one problem. The video did was not clear as to the proper orientation of the blade seal with respect to the seal taper. I first installed the seal with the taper pointing outwards. The result was leakage and noisy operation. I found a second source that specified a definite orientation of the seal; that the taper should be pointing inwards. After turning the seal around, the leaking stopped and the dishwasher ran quiet. Success! I suggest that you update your installation video for the upper door seal to make this more clear. Thanks.