Hi, I have a 2016 Mazda 6 Tourer 22d SE-L Nav. Recently when I open the car with the remote key fob I notice the central locking keeps locking / unlocking a few times instead of just opening once.
It never happens when I lock the car, just when I unlock it and always first thing in the morning after it has been standing overnight, and then randomly during the day.

Any suggestions / advice would be greatly appreciated.

 

Sounds like one of your doors has a problem with the unlock mechanism travel. It will cycle until it reaches the correct travel.
It'll be a case of trial and error to check each door / button for normal travel, if one is a bit sticky you might be able to see it, but more likely it'll be in the mechanism inside the door.
You'll have to pick a door to start with and check the mechanism for smooth operation, maybe just holding the locking rods gently as you try lock/unlock, giving it a slight assist if it feels sticky. Then a good lube of all sliding points using silicon grease. Start with the doors that get opened & closed most (normally drivers & passengers). Then onto rear doors and boot if all seems OK on the front doors.
I'm not sure whether the dealer diagnostic tool can interrogate the body control module to identify which door is causing the unlock / lock automatic cycling, Might be worth a phone call to ask the service manager at your local dealer whether IDS/VCM can read central locking diagnostics. Would save you a lot of time & you could still fault find on the identified door solenoid after that.