My Bosch shx46A05UC no longer will drain.....it

I ran into the SAME problem with my Bosch SHX46A06UC /21. The problem ultimately ended up being a clog in the air gap vent, (meaning, SOMEBODY ran the dishwasher without the bottom filter being in place or not in place properly). Remove the air gap cover and upper surface nut to drop the air gap vent into the area under the sink. Disconnect the hoses from the air gap vent filter (placing a bucket under the hose from the dishwasher). Run the drain cycle on the dishwasher. The washer should drain into the bucket and let you know that your pump works and that there are no clogs or kinks in the drain hose. (This will also remove the clog if so). The air gap vent's smaller hose connection is MOST LIKELY where your clog is. Look at the upper end of the air gap vent. You'll see a couple of clips on opposite sides of each other, that hold the air vent cap in place. Using a small screwdriver, (or your hands if you can), depress the clips (or one at a time) to get to the point where you can pull the vent cap off the filter. Either use water or a thin, long blade screwdriver to force any objects out of the filter. You should now have full flow through both branches of the filter. Using water and a rag, clean the vent cap and filter. Mount the air gap vent filter back onto the sink. Reconnect the hoses and remove the dishwasher's internal filter(s) and clean them as well while you're at it, making sure to remove any debris that might remain underneath the filter and has the chance of clogging the unit again.

Run the washer again to test. You should be good!

Cheers!