My 997 2005 Carerra Cabriolet, since recent new battery installed, has been locking itself automatically with or without the key inside and regardless of top up or down. Never did that before. How to stop it? It is annoying and could be really a problem if key left in by accident or purpose with top up and
windows closed.

 

Does your cabin light come on when you open either door? Does it do it if you unlock it and then open the passenger door? Does it do it if you unlock it snd open the driver's door? Have you changed the battery in your key?

 

When you say that the battery was changed do you mean the battery for the car or the keyfob? If for the key, then maybe when you took the key apart to change the battery, you somehow tweaked the lock button so that it now presses itself when you go over a bump or something and the car locks itself.