Hi my last good remote key fob is dying so I have resorted to locking the car manually with the key for the time being.(1998 996C2 UK model RHD)
When I lock the car via the keyhole in the drivers door, the driver door locks but the passenger door never does. The passenger door does lock when I manage to get the remote fob to work by fiddling with it so I know the pass door lock is OK.

When I lock the car manually with the key the following happens:
1)the drivers door locks
2) the pass door and gas cap do not lock
3)the instrument pod lights go out (suggests signal is getting from the door to the dash )
4) Interior light doesn't go out- stays on for the normal length of time
5) Alarm doesn't arm

when I unlock the drivers door manually using the key:
1) Drivers door unlocks
2) Interior light comes on (before i open the door)

The lock button on the dash locks both doors everytime no problem

I was originally going to start investigating at the drivers door lock however now I see that the dash lights and the interior lights react to the key being turned make me think the problem may be elsewhere. any ideas??? thanks.

 

That is the behavior my 02 Boxster has and I think my 03 Turbo. I think it is normal behavior not something amiss. The behavior is probably covered in the owners manual but I have not bothered to look for it.

Update: I did look for the info in my Turbo's owners manual and didn't find anything on this behavior. At the car I did not try to turn the key in the lock several times in rapid succession to see if this locked the passenger door.

 

I never even thought of that option! you may well be correct ,I'll need to check my manual and see if it mentions anything. Might have to shell out for a new remote sooner than later . Thanks