Dash light says boot is open when its closed

[Byork]

morning all , having googled this it seems to be a common problem but cant seem to find it on here,

,ive got a A4 2007 estate and the dash says the boot is open when its not and the alarm keeps going of , i have had  problem with a leak from a split water pipe  at the hinge area of the boot , so i think the sensor has got wet. so what i need to know is is the sensor part of the boot lock? can i get a new lock of evil bay and would this solve the problem? 

thanks in advance