My key will open my trunk, but not unlock my doors or start my car.

Where else do you have locks? A locking glove compartment often has a separate key. The main key is supposed to open the door, open the trunk and start the vehicle. The other key is a Valet Key, the key is intended for people to give to valets to park their cars or to repair shops to use. The valet key will open the car door and start the car but will prevent someone from unlocking the glove box or the trunk.

Try lubing the lock cylinders with dry (never use wet lubes like WD40) spray comes in a little tube you just squeeze it and spray the dry lube into the lock to see if it frees up the lock cylinder. You can buy dry lock lube at any hardware store.

I assume you have the correct key. (sorry, I have to ask) For all doors locks and the trunk lock to not work, at the same time, is very unusual.

Try squirting some light oil in the locks, like WD-40, then push the key in and out a few times.
Wait a couple of minutes, and then try to unlock the doors and trunk.

If you still cant get in the car, and your 100% positive you have the right key, call a lock out service.

They can get it open, and your insurance may cover it. Hope this helps.

This is the key security system. Somehow youv'e set it off. Used the wrong key tried to open the door with the alarm on. Opened the door or trunk from the inside after locking it from the outside. If your the real owner of the car it'll be no problem to get it fixed. If you have the correct key lock the doors from the outside with the key and lock it twice ( the doors ( all of them ) should lock). Leave the car alone for a minute, maybe 5. Then unlock the door twice, all the doors should unlock the second time. Enter the car and start it with the key. If you with a remote door lock fob that can work too. If this fails then try a different door or even the trunk. Sometimes the driver doorlock switch wears out or gets ice in it and unlocking a different door or useing the remote can get you going again.

The trunk lock is incorporated in the central locking system. This means that you can either lock or unlock the trunk by means of either of the front doors. You can also operate the trunk lock directly with the master key even if the vehicle is centrally locked.

Are you sure it is the Master Key? Try the key in the glove box lock. The power door locks should unlock the trunk for you turn the key if it is right over to the right turn it right over to the left . you turn the key to far right to stop the boot been opened when the doors are not closed.

Keep us updated.

Assuming the car battery is ok (if not, buy a male to male cigarette lighter at the auto store and connect to another car until charged enough to unlock the doors...but don't try to crank the ignition!). The trunks won't open if the battery went dead with the alarm set because arming the alarm physically locks the releases.

Sounds like the key code is switched off because you replaced the key fob battery. Try unlocking the car manual with the key in the door lock. Then switch the ignition on to reactive the keyless entry. If this does not work, you might also try pressing the fob unlock button with the key in the door lock until the dash led flashes.

jimmy: it sounds like the drivers door unlock tamper switch or the other switch may have failed. One side can affect the other under certain circumstances. Your trunk lock also has a switch which arms and disarms the antitheft system. Try locking all the doors, make sure the hood and trunk lid are closed and then open the trunk. Leave it open open the drivers door and try to start the car.
If it's a no start. Disconnect the ground battery cable then put the ignition key in the run position in you ignition switch. Reconnect the battery and try to start the car. It should start. This usually will override the anti theft system. One issue with this will be, whether the antitheft system will remain disarmed.
Although I have never tried this before, I know that the system will not arm unless all the doors, trunk and the hood are closed.
I could suggest this to try if the car starts as I had told you pertaining to disconnecting the battery cable, I would take the switch and unbolt it from the passenger's side of the engine compartment just forward of the shock tower. Just let it sit somewhere so it doesn't get caught up in anything moving. If there is a light under the hood of your car, remove the bulb.
Let me know how you make out.

To carry out this procedure you need to have one working key and one key which requires programming. It may help sometimes to hold the key close to the rear view mirror as this is where the sensor is located in most models. 1. With both keys, get in the car and close all windows and doors. 2. Put working key into the ignition and turn to position 1 (the accessories should turn on) (try also position 2) 3. Turn the key back to position 0 and take the key out of the ignition. 4. Using the working key, hold down the unlock button, press the BMW logo (lock button) 3 times, and release the unlock button. Doors should lock and unlock. 5. With the new key, hold down the unlock button and press the BMW logo (lock button) 3 times and let go of the unlock button. Doors should lock and unlock and you're done!! If not working try the following PREPARATION 1. Close all doors, trunk, hood and sunroof. 2. The security system must be in 'disarm' mode. The key must be removed from the ignition key slot. ENTER CODE LEARNING MODE 3. Open trunk and leave it opened. 4. Open the drivers door and sit in the drivers seat. 5. Close the drivers door. 6. Cycle the ignition switch 5 times between the 'OFF' position and position 2,(ignition 'ON', all dash warning lamps will illuminate). The red status LED will illuminate continuously, and the siren will 'chirp' once, to indicate that the code-learning mode has been initiated. ?Do No start the engine.? The Ignition switch cycling in step #6 must be performed within 10 seconds. The sequence in steps #1-#6 must be performed within 45 seconds. REGISTER/DELETE ID CODE(S) 7. Open drivers door, (remain seated in the drivers seat) 8. Close the drivers door. 9. Press and release any button on the remote you wish to register in the system. The status LED will shut off momentarily to indicate that one code has been registered. 10. Repeat steps 7 thru 9 to register the three ID codes. It is possible for the system to memorize a total of 4 different ID codes. As a new code is initialized into the memory, the oldest code is automatically deleted. If you had lost your remotes and wished to delete the lost remote ID codes from the memory, you could initialize the ID codes from a newly purchased replacement transmitter four times thereby deleting the previous ID codes from the system memory. EXITING CODE - LEARNING MODE: 11. Open drivers door, and exit from the vehicle, leaving the door opened. 12. Close trunk. 13. Close drivers door. The LED will turn off and the siren will 'chirp twice. 14. The initialization procedure is now completed; Test all remotes to confirm operation. If this doent work your alarm/central lock needs to be reset

I may be able to help if you havent fixed it yet. I believe I had the same/similiar issue...

I would make sure all of the doors were locked with auto lock button on inside of door, then I would shut the door so all doors were locked from pressing the inside auto lock button. then I would use my key to unlock the trunk, open the trunk and close it leaving it unlocked. then i would use the key to unlock the drivers door and the security would reset... if not then unhook the battery for a few minutes then hook back up and see if that works.. glgl

I locked the 2000 lincoln continental with the key fob but lost it now the ignition key wilolo not unlock the door