E30 is a motor fault and E31 is a tacho fault. the tacho is the small magnet on the rear of the motor which has a coil around it and it sends out information to the control board to let it know if the drum is out of balance or not. If the magnet in the center of the Tacho has come off or the wiring to it has shorted out, the motor will instantly go into full spin, if the magnet has come off you will be looking for a slate grey disc about the size of a 1£ coin with a hole in the center,a small washer and a screw,these may now be under the machine. Also Check the motor brushes for excess wear (if either of the two brushes are pitted and sooty they both need replacing)
casper/www.selfixuk.com, April 2006