Pros: This is an easy way to clear clogs, but is not documented
Cons: Bosch should have put this 'fix' on their web site years ago.
The machine is a bit different than most washers, so here is help when you get "error 04"...Your pump is plugged. There is a round 'door' on the lower front of the washer. At the 5-O'clock position in the door there is a small hole. Put a small screwdriver blade in the hole, push in (just a little), and you can rotate the door clockwise. When the hole is in the 6-O'clock position, the door will come out and you can get to the problem.
Immediately facing you is a black connector, about 4 inches (10cm) in diameter. When you unscrew this, all the water left in the washer will spill out onto the floor. (We used a pile of towels to catch this). The Black connector unscrews counterclockwise, and takes quite a few turns. Once you have it out, you'll find the source of your clog. In our case, it was a childs sock. We removed it, screwed the black connector back in, and the washer ran fine.
After a couple of loads (to make sure there was no leak) I put the door back on...and rotated it to the 5 O'clock position. And thats it!
You saved yourself about $100 service call, and probably a ton of time waiting.