Bosch washers come with built-in sets of error codes used to diagnose and correct common problems. The E27 code isn't often listed in Bosch manuals but relates to the washer door lock.
The door lock doesn't properly close or the door lock sensor is not sending the proper message to the washer machine controls.
The E27 error flashes on the washer LCD screen and stops the current load. Unplug your washer for 30 minutes and then plug it back in to reset the code.
Open and close the door two or three times to reset the sensor. Sometimes the door has been closed too hard and the sensor reading fails.
Replace the door lock assembly on the washer. Refer to your washer manual for the correct part numbers.
Check to see if your Bosch washer is still covered under warranty. If so, you could receive free replacement parts and service for the faulty door locks.