The key opens and locks the left or right door but using the procedure to lock and unlock all of the doors (turn the key and hold it) does not work! It only locks or unlocks that door. With the engine on the switch on the drivers door will lock or unlock all of the doors. Do you have any Idea where I can start looking to solve this issue?

 

I didn't know our cars had that feature. I just use the remote key fob.

 

u don't hold it you turn it twice

 

you turn it once to open that door.. then you turn it again but this time you hold it. this should open all doors.
if it still doesnt work.. replace the sensor behind your door handle