My driver's door lock quit working yesterday. With the remote, all other doors lock and unlock and the soft button on the drivers door also locks and unlocks all other doors as does the switch on the drivers door. I can manually lock and unlock it with the lever and the key. I'm assuming that means that the lock actuator assembly needs replacing. Has anyone else had this happen? Did you end up replacing the entire assembly (the part costs between $240 and $350) or can the actuator portion of the assembly be replaced separately?

Thanks in advance for any help!

I have/had the same problem on and off on my 2009 M35X over the last year.

This malfunction is also problematic because if you "lock" the car and the driver's side doesn't lock and you open the door the alarm goes off!! I thought I had an alarm problem and spent $120 unsuccessfully of dealer time trying to diagnose before I decided to diagnose myself and I realized the issue was the door lock.

My door has fixed itself which probably means there is a short somewhere. I think you are looking at almost $500 total to replace door actuator if that is even the issue. If it is totally broken, that should be easy to diagnose and fix, otherwise you waste lots of time and money for the dealer to fix an intermittent problem.

Not really a great answer but the auto door locking feature causes this actuator to prematurely wear (in all cars) and will be an expensive issue to fix as cars get older.

Thanks Bluedevil - I spent most of last night online trying to find the best deal for a new actuator assembly. Luckily I didn't buy one - as tonight it suddenly started working and seems to be working every time again. I had the same problem with another car about 6 years ago, bought the actuator assembly and by the time it arrived, it started working again. 6 years and 120,000 miles later it still works perfectly and the new actuator sits in a plastic bag in the garage. I'm wondering if it is related to the amount of rain we've had lately - we had about 8 inches of rain in the first 8 days this month and now it has been dry for a couple of days. I think I'm just going to wait this one out and see if it starts acting up again.

kmiles, i have had the same issue with my 06 m35x...i dont know how cold it is where you are but here in central ny it gets really cold and the day my door did not open it was -15* f!! but the day before it was in the +20's and snowed a bit....i think with my situation some moisture got into the lock on the drivers side and caused it to freeze...i had to run my car for over an hour on 90 for the climate control...it eventually unstuck it self and i was able to get in normally...one thing i did do on a warm ish day was to put some lube on all the moving parts i could get to!! this will also help prevent moisture form being able to freeze in the moving parts!!