Since I had this problem last winter when I bought the truck this past summer I disconnected each sensor and put some DiLectric grease on the connector and reinstalled.

 

This happens to me all the time in the winter, never once did I think it was a problem, just figured there was a layer of sand/salt/snow/ice/mud or one of the other joys of winter covering the sensors up.

 

Mine have been like this for a week. cleaned them off and still the same. Maybe i'll try putting the truck in the heat overnight and greasing them up as well.

 

This happens every time I wash it (I've only had it for a couple months so it's always been cold). Until yesterday it's only been the far right sensor, but yesterday it was both outside sensors. I've never once had this problem with my Volvo or Dodges.

 

My truck present the same parking sensor issues , few days ago, but today I decided to investigate "Why is intermittent?"
In fact it is the cold, today I put my truck inside the garage at 20 degrees Celsius and everything works fine, when leaving the garage with temperature at -4 degrees Celsius, after few minutes the problem returns.

it's not snow or humidity, the weather is totally dry.

 

Same