My induction slide-in range was getting an E15 error code. First thing to do is look in the service manual, which should be in a plastic pocket at the back of the oven. I eventually did do that, but first I googled it.
First, power cycle the stove, i.e. turn off the breaker, wait a minute, then turn it back on. That fixed it for a few months, but then it started doing it again, except now it only took a minute for the oven to beep E15 after turning the breaker back on.
The service manual said says an E15 error is a communication problem for the ESEC-UIB Board and to check the harness, replace the board. I took off the front casing and checked the cables and the board. Everything looked ok, but restoring power still got me the E15 error.
Capacitors take time to charge, so I suspected it was a capacitor problem (google "capacitor plague" if you're curious). Sometimes a bad capacitor bulges at the top, but mine looked ok. Better just replace the board anyway.
Turned off power to the range.
To get to the ESEC-UIB Board, I needed to take the bottom casing off the control panel at the front. To do that, I had to take off the vertical edge panels. To take off an edge panel, remove the 2 visible screws on the side. A panel will still rest on three other screws. The panel pulls back (toward the back of the oven) from the bottom two resting screws, but then you have to push the panel up and back to get it off the top resting screw.
There are 6 screws holding the front casing. Two at the bottom above the oven opening and two at each side. The ones at the side screw in straight up (look in the deep holes). The casing pulls off straight down.
I found the board (using the image in the service manual) and unscrewed it from the oven. Then I took off the cables. The ribbon cables are tricky and needed a little screwdriver inserted in a notch to get under the connector (not under the holder). Don't pull on the ribbon. The other cables have push-in clips.
I replaced the board, re-attached the cables, screwed the board back in, then restored power. Oven did not complain after a half hour, so I turned off the power again and assembled the rest.
So far, no problems. That seemed to have fixed it.