[thom4782]

When you try to lock the door, do you hear two quick horn beeps? This happens when there is a problem with the central locking system.

I'm speculating that a Durametric might help. It should tell you if the central locking system is throwing codes that might narrow down the problem. It may allow you to activate pieces of the central locking system to see what part might be causing the problem. I'm going to test this when my cable arrives next week.

I had a similar problem - not with the key, but with the locking switch on the central console. The LED would come on without me touching it. When I pushed to rocker to turn the LED off, I would get two quick attempts to unlock the doors even though I never locked it in the first place. Once the LED was on, the remote key acted crazy. The independent's code reader said there was a central locking synchronization problem although the specific problem wasn't diagnosed.

It looks like my passenger side door latch was faulty. I found it was the culprit when I could throw the system into its crazy behavior by opening the passenger door handle. Occasionally, the window would go back up if I released the handle or do other weird things

Good luck.