I have an intermitant fault with my transit minibus. Occasionallt the display on the dashboard shows the front passenger door open when it's not open. The result of this is when you lock the van with the keyfob/central locking, the horn sounds and the door unlocks again. So far I can't figure out what the problem is because any sensors or switch on the door are not immediatly visible. has anyone heard of this fault before. If so is it easily fixable. My local dealer haven't a clue!!!