rear doors open on V40 while driving

Thanks Chris I have done that. Also the problem occurs even if all rods are disconnected from the lock. I am beginning to think that it is the lock mechanisms themselves that are worn, even though they initially seemed to work okay when removed from the car. I have removed one again and by fiddling with the the opening catches I can get it to lock, but then I can open the lock by pulling with my fingers. This seems to me to be the only explanation for why the doors seem to shut with a click (as per the lock engaging) but by pushing from inside you can open the doors without using the handles. What do you think? I would hate to shell out on two new mechanisms if the problem is something else, really simple, which I have overlooked.

Could it be connected to the child lock system and do they still open when ths is on. I find it hard to believe that both would go faulty at the same time. Sorry if you have tried this already but it's always good to get ideas from people that may have been overlooked. I know this from experience

Yes, they still open when child locks are on. I agree it seems bizarre that they should both have gone at the same time. Thanks for giving this problem some thought Chris.

agree its the catch plates on the body being too far inward for the lock to catch, the door stops are holding the door off.. The plates are tight but if you put some release fluid on them, and then a day later load the allen key inward as you turn, it should come free... make sure you have a tight fitting key.... Note if you cannot shift them you may be able to get a cold chisel to the back side of the catch plate and tap them outward.. this may seeem extreme but its basically how we do it on body adjust on the final assembly inspection lines in the factory... Best of luck....