This is a porsche cayanne 2008. the windshield wipers on my vehicle will suddenly stop working. this issue can happen if the car is in motion or stationary, street or highway driving. it is very unpredictable. the wipers can stop operation for a variable amount of time. at times i have to turn off the car to get them to work again. sometimes they will remain inoperable from seconds to 15-20 minutes, and restart on their own. at times if i am driving in the rain the windshield wipers will cut off and not restart or restart after a period of time, preventing proper visibility.