I have a 2006 325i. I can't lock the doors using the remote but I can unlock it. I had to use the key to manually lock the doors. What is the problem?

Lock/unlock motor may be failing. Remove the door panel and remove the connector from the lock motor. Check the dc voltage at the connector while pressing the lock switch. If you see battery voltage, replace the motor. If the voltage is low, inspect the wiring.

stick key in driver door lock and unlock it. If that works, now see if the remote will unlock the door or doors..i remember reading in an owners manual once where you can program which doors open and close by they way you press and hold down the two main buttons, also after a battery change in the remote, i think, but not sure, i did this on a blazar i once owned... the owners manual said, that you had to be within 20 feet and press and hold down both buttons till it makes the arming sound.... Can i get some feedback cause im curious..thanks.

1. Driver's doo opend and unlocked, all other doors closed and locked
2. Inser Your key in ignition, don not turn, remove key
3. using the manual lock/unlock button on ther dirvers door, slowly press lock and unlock 5 times (count the lock 5 times and unlock 5 times)
4. Shut door
5 Open door
6. Using the lock/unlock button on the direvers door, slowly press and unlock 5 times (count the lock 5 times and the unlock 5 times)
7. With the door open insert you key into the ignition, turn to ON position (don't start), wait 5 seconds. Trun off and remove key.
8. Locks should cycle once (Car will lock and unlock once). If they don't cycle or they cycle more that once, do stips 1-7 over.
9. Using the remote, push lock button, hold for 1 second, release. The locks should cycle once. If not start over and go slower.
10 Close the door. Open the door. Press the lock button on the remote. The locks should cycle. Close the door. Press the lock button on the remote, the doors should lock. Press again and the doors shoud unlock.

I got this from a site called FixYa (don't have URL). It took me a few tries but it worked like a charm.

1. sitting in driver seat, with driver's door OPEN, press lock/unlock button ON THE DRIVERS DOOR to lock all doors, then manually unlock driver door only.
2. Insert YOUR key in ignition, DO NOT TURN, then remove key.
3. Using the same lock/unlock button ON THE DRIVERS DOOR, slowly press lock-unlock in 5 cycles
4. Shut door.
5. Open door.
6. Using the same lock/unlock button ON THE DRIVERS DOOR, again slowly press lock-unlock in 5 cycles
7. With the door open insert your key into the ignition, turn to 'on' position (DON'T START), wait 5 seconds. Turn off and remove key.
8. Locks should cycle once (Car will lock and then unlock once by herself). If they don't cycle or they cycle more than once, do steps 1-7 over.
9. Now using the remote, push lock button, hold for one second, then release the button. The locks should cycle once. If not, start over and go slower.
10. Close the door.
11. Open the door.
12. Press the lock button on the remote. The locks should do a lock-unlock cycle.
13. Close the door
14. Press the lock button on the remote, the doors should lock.
15. Press unlock button and the doors should unlock.

1. sitting in driver seat, with driver's door OPEN, press lock/unlock button ON THE DRIVERS DOOR to lock all doors, then manually unlock driver door only.
2. Insert YOUR key in ignition, DO NOT TURN, then remove key.
3. Using the same lock/unlock button ON THE DRIVERS DOOR, slowly press lock-unlock in 5 cycles
4. Shut door.
5. Open door.
6. Using the same lock/unlock button ON THE DRIVERS DOOR, again slowly press lock-unlock in 5 cycles
7. With the door open insert your key into the ignition, turn to 'on' position (DON'T START), wait 5 seconds. Turn off and remove key.
8. Locks should cycle once (Car will lock and then unlock once by herself). If they don't cycle or they cycle more than once, do steps 1-7 over.
9. Now using the remote, push lock button, hold for one second, then release the button. The locks should cycle once. If not, start over and go slower.
10. Close the door.
11. Open the door.
12. Press the lock button on the remote. The locks should do a lock-unlock cycle.
13. Close the door
14. Press the lock button on the remote, the doors should lock.
15. Press unlock button and the doors should unlock.

Long beep to follow if successful.

Remote Programming Instructions

1. Driver's door OPEN and unlocked, all other doors closed and locked.

2. Insert YOUR key in ignition, DO NOT TURN, remove key.

3. Using the MANUAL lock/unlock button ON THE DRIVERS DOOR, slowly press lock and unlock 5 times (count the lock 5 times and unlock 5 times).

4. Shut door.

5. Open door.

6. Using the lock/unlock button ON THE DRIVERS DOOR, slowly press lock and unlock 5 times (count the lock 5 times and unlock 5 times).

7. With the door open insert your key into the ignition, turn to on position (DON'T START), wait 5 seconds. Turn off and remove key.

8. Locks should cycle once (Car will lock and then unlock once). If they don't cycle or they cycle more than once, do steps 1-7 over.

9. Now using the remote, push lock button, hold for one second,
release. The locks should cycle once. If not, start over and go slower.

10. Close the door. Open the door. Press the lock button on the remote. The locks should cycle. Close the door. Press the lock button on the remote, the doors should lock. Press again and the doors should unlock.

Needs new drivers door lock actuator (P/N 3B1-837-015-AS)

there could be a problem with the actual remote, get it checked, if you do need a remote plz get it from a mercedes main dealer.

I have an A4 and did this to re-program my key:

1. used the key to start the car...then turned it off
2. put the key in the driver door (door closed)
3. pressed the lock button on the key fob once
4. turned the key to lock the door.

This is basically the steps in the owners manual, but the car must be started with the key first, and the key must be in the door lock before pressing the lock button.

sounds like the drivers side key switch has failed remove the interior door panel and there will be a switch attached to the back of the key lock cylinder or around there it should be two or three wires also check the door jamb wire harness where the door closes for any broken or damaged wires, use a vot meter and see if you get power or ground to the opposite side of the switch when you use the key to lock and unlock the door if nothing changes and there is power or ground! at this switch i would replace it, i don't think there is one but if the car has a passenger side key hole try to unlock the car from that side and see if you get the same problem -jeff