hi guys. theres never a problem with the knock sensor itself, we have never sold one here and prob never will,
every prob we have had so far is the wire loom the comes from under the tank/airbox and gos to both the knock sensors always melt with heat, now they are a shielded wire and will 9 out of 10 times need replacing. i have heard of a few guys trying to fit new plugs etc and had no luck... i am one of them guys.
i have 2 st1300s with the problem here now, and i have one that is still throwing the sensor light on, i have replaced the loom as it was melted badly and also found a melted plug under the throttle body going to a injector, so i fixed that to.
but... the code still comes up, theres a way to see if yours still have a fault but placing it on the centre stand and holding the revs at 4,500rpm for 5/6 seconds. then a drop in the ecm map will bring on the light untill you reset the fi, ie turning off the key.
i have had many of these cases and have always fixed the problem. but this one has passed all the tests and checks and now the only thing it can be is the ecm has been spiked but the sensor wire.
note, as pete said, the bike will run fine and will not cause damage it will need looking at soon. if i can help please ask. on anything you may need.
and ps. thanks pete for the nice remark towards me.