Just tried this, and will check in the morning for results. As it turned out, I was able to connect directly to our hot water line that goes to the washer, so am hoping that contributed to the eradication. Why do you suppose the soap makes any difference?
Update: I think the problem is that sometimes they build sections of the nest in a way that can't easily be flooded out. So far the best non-chemical solution I've found is to take a clear glass bowl and put it over the hole at night. I put a heavy rock on top of it. The wasps don't "get" that their hole is blocked because they are programmed to see daylight and not figure on creating another pathway. It just starves them out.
This is terrific info, thank you. I just did Bimmer-yoga replacing this fuse. I suspect it may be connected to the cig lighter, as I used that yesterday and smelled something electrical. Then the locks stopped working. After the gymnastics, I did find/replace this fuse and all is well (for now!).
I'd to 4 stars, though I thought the tires they put on the car were some brand I'd never heard of before. They are a subsidiary of Cooper it turns out. Anyway, the follow who runs the place is pretty nice, and they did service my car pretty quickly.