Even in diagnostic mode this models control will happily point toward a problem with the safety float or switch which may not be the problem. Try resetting the control using the following two steps:
1) With the door closed and the dishwasher turned on, press and hold the Start button for 5 seconds. If your model has a display it should show "01" of "00". Press the On/Off button (turning the dishwasher off) and the control should be reset.
2) If step one didn't work, remove the toe kick and disconnect the drain pump wire harness from the drain pump. Make sure the connector isn't touching anything, tape it if necessary. With the door closed, press the On/Off button turning the dishwasher on. You should hear the control turn on and the relays click on and off. Wait about 30 seconds with the power on, then press the On/Off button to turn the dishwasher off. With the power off, reconnect the drain pump harness and reinstall toe kick. With the door closed, press the On/Off button to turn dishwasher on. The control should be reset.
Source: Bosch SHE6AF02UC/02 Drain Pump Keeps Cycling