The E2 code indicates that their is a positional error on the valve. This is caused by the actual position of the rotating valve not agreeing with that demanded by the electronics unit after a full rotation. It is normaly caused by the position sensor board on the rear left of the valve (when viewed from the front) being heavily corroded. It is secured in position by two screws to the steel top cover and is then connected via a portion of the ribbon cable to the electronics box. The fine leads of the opto sensor are visible on the board and salt spillage causes them to corrode through. The top sensor emmits infra red light to its associated receiver, which is in alignment a short space away and below the disc. The top valve disc is located between the two sensors. Rectangular cutouts in this disc, at set positions, allow the infra red to pass through to the receiver when a slot is in alignment between them. The board is fiddely to remove, as the top disc of the valve is centered between the top active sensor, therefore the board must be removed sideways to clear the disc. On later models, a cut-out in the side of the moulding permits this to be done more easily. The corroded component wires after cleaning, can be often be joined with solder and then covered in Araldite to protect them from future corrosion. When reffitting you must ensure that the disc is correctly located in the gap between the sensors befor securing it in position. When power is re applied, ensure the valve is in the normal Service position, with water pressure, as this assists the valve to rotate. After one revolution it should take up the normal Service position with the previously set Clarke number displayed.
Kayball, October 2010
