My car has the same issue (2006), and it’s very annoying! Any idea where this sensor is? I’ve cleaned the area pretty well and even sprayed some electric contact cleaner up into the locking mechanism area in hopes of fixing this issue…no help.
Finally, it seems to get worse on my car in the cold weather, ie. in the summer it’s intermittent, in winter it’s always tripped. This also means I cannot use power locks and alarm sounds when I can lock the doors!