i cant understand why its burning through the sensors it never done this before
As said above you could disable the sensor or buy an after-market wideband kit as they might last a lot longer , did you check the wire connections at the ecu ?
You would be better getting a full under car/rear diffuser, unless its just for looks lol
if you are building a front diffuser it is worth noting that it will only create proper downforce if it is strong enough to support your weight - i.e standing on it