Had the same problem with mine. Check that the reader (behind the plastic facia) has not fallen down, sometimes the reader unclips itself when you push the card in. I had to superglue mine in place.
Bob
September 2010
do you mean you put it onto code reader and it came up with a fault? if so depends on what the fault is. or do you need to put on code reader? more info would help in giving an answer.