2002 Volkswagen Jetta Distributor cap

A 2002 Jetta doesn't use a distributor cap it uses a more advanced ignition system called a coil pack. (It's all electronic) I have already replaced mine on my 2001 Jetta GL. Water should not get inside it unless it is somehow cracked. It would probably misfire every so often if it was that sensitive to moisture. It must be an electrical system problem if the car is not making any noise. I would first check your battery terminals to see if you have corrision and the wiring system. It is around $140 for a new coil pack from the dealership plus labor. I have seen a testing module for $60-70, but I am unaware of anything else.