Code 128 : Water sensor

[Comet]

Can any body shed some light on what a code 128 : water sensor means? The water temp on the display went up to 110 degrees a couple of times but both fans kicked in and reduced the temp accordingly although the first fan didnt kick in till 103ish - sounds far too high to me! Also didnt get any steam from the bonnet which is what i was expecting so could it just be a faulty sensor? or something more major? (hopefully not) Any ideas anyone???