Error 51 is the diverter valve, located next to the drain pump with 3 hoses attached.
Turn the power off on the machine but leave on at wall. Measure the voltage across the wax motor ( the brown unit attached to the diverter valve with 2 wires ). If you get a reading of 230 volts ( 110 in the US ), then the computer will have to be replaced as well as the diverter valve.
Paul Levy, December 2007
