The operation of the passenger side front door lock is intermittent. It always locks but sometimes does not unlock. It can be unlocked manually from the inside. No fault codes. Any suggestions as what to check first. When it does not unlock I do not think the solenoid is moving.
Should have said its at 2005 X350 4.2 sport normally aspirated.

 

I have a similar fault but on the driver's door which locks but never unlocks unless I use a key.

The actuator is at fault and you will find that it will never unlock eventually.

The solution is to replace the passenger side actuator which is not cheap unless you get an used one.

It is a good idea to have the "drive away locking" deleted so that the door is not locked when you come to stop

and need to open the door. These days a good indy will have the software to do it so you don't need a dealer.

If you decide to do that get in touch and I will give you a tip re software.