BMW E36 Forum

Key Fob is not working as the lock and the unlock buttons have worn away, the fob still works when pressing the boot. Have been using the key to manually open the car door. When the weather dipped the key would just turn and not open the car and would turn more than usual.

AA came out and using air bags to create a gap at the side of the door we opened the bonnet with a hook. Using slot 16 in the diagnostics cap we could then press on the electric windows to open. The driver’s door would still not open so we opened the window on the passenger side and opened the door with the internal handle. The key was put in the ignition and all the lights up as normal but the car would not turn over.

Is there a separate immobiliser in the door mechanism that would stop the engine from cranking up?

Sorry but sadly it sounds like you need a new key and they don't come cheep.
The reason you can't start your car is a chip in the key for the imobiliser and when the batt goes flat in the key it stops working. It sounds like the key is in poor condition anyway but a BMW dealer will be able to get you a new key (around about NZ$600 I have heard).
As far as the door locks go if you lock your car with the key then none of the doors, boot or fuel cover should open or unlock unless you use your key (it is possible to lock people in).
Pushing the buttons down just locks the doors and boot leaving the fuel cover unlocked.