PDC problems
 

Whenever PDC is engaged the front 2 sensors go crazy even if there is nothing ahead of me. Any ideas what can be causing this?

Were you driving in the rain? Mine does this in the rain sometimes.

At the risk of sounding obvious, have you checked to see if one of your sensors might be dirty? I've experienced this once after a long winter road trip after the car dried off. I cleaned off my bumper and brushed out the little groove around the sensor and it was fine. Worth checking.