knock sensor?

Ok my cars sitting now, the other day my CEL came on with a knock sensor code thrown up, What is the possabilites of a problem here?

Back knock sensor perhaps. If you could log it, odds are you would see timing held to a fixed value, 3 degree if I remember correctly. Could also be a break in the wiring or something, hard to say over the internet. But as far as I know the only knock sensor malfunction that can be detected is if its really shit the bed hardcore, or is no longer connected to the ECU for one of various potential reasons.