Thanks MB Doc. There are 2 sensors, a larger one for the fans (I think), and a smaller one. Is it the smaller one you are talking about? If this is the one that measure pressure, then maybe its busted. I was going to measure the resistance across it, but I don't know what it should be anyway, so didn't bother. And of course you can't jumper these sensors any more.
Am I right in thinking that the EC light should go out if it sees pressure at that switch?