Central locking not working, can lock all doors but cannot open centrally

[JAAUDIA6]

Hi, I have a 2004 Audi A6 2.4 Avant Auto with the following fault:-
I cannot lock or unlock the doors via the key fob, (could be battery but cannot open the key) Anyway this is not the major fault which is :-
When the car is locked by way of key in the door or the drivers door switch, all the doors lock and the boot as well, but when I press the unlock button on the drivers door nothing happens, likewise when I turn the key in the drivers door, it will open the drivers door only!
It is also NOT possible to unlock the other doors from inside the car by pulling the door handles UNTIL the key has been put in the ignition and put on standby position, I hear a relay click in the doors and then you can open the doors manually by way of opening the door handle. (I think the dead-lock is engaged on the other doors until the ignition is switched on. Does anybody know of this fault or condition? and can anybody suggest a solution. Thanks in advance.

[NickPicks]

If I use the door key to unlock, it only unlocks the driver's door, and all the other doors remain deadlocked until the key's put in the ignition, the central locking button won't work until the ignition is on either, so it sounds like your physical key is working correctly, but your fob remote isn't.

Try changing the batteries, but sometimes, if the battery has been flat, then the car needs reminding that the fob is allowed to work. It says how to do this in the car handbook, but from memory, I think it's:

lock the car.
press the fob unlock button.
within 30 seconds, unlock and lock the driver's door with the key.
Now the fob should work.

You could try that first to see if yours has just forgotten the fob.

Edit - checked my old thread about this and corrected the method slightly.

[JAAUDIA6]

Hi Nick, thanks for the information re the locks when opened by key; that was something I was not aware of.
I have tried to open the key but it has been butchered before and without destroying the key I don't think I will be able to open it.
I did order another key from ebay but haven't been brave enough to try and swaps inards around.
One thing that bothers me re the central locking is that the unlock switch does not operate inside the car with or without ignition on,
on my A8 I had the switch would operate in either state.

[NickPicks]

Once the deadlocks are off, the central locking button on the door should lock / unlock all the doors. It's only when you first open it with the key that it won't work until you turn the key in the ignition.

Opening the key is fairly easy:
use a small screwdriver in the slot on the reverse (side without the buttons) to split the front section awayfrom the button section.
lever the button section apart by pulling apart the sides where the key blade went (2 thumbs should do this)
replace the batteries (mine uses 2 x CR1620)

[NickPicks]

If you're buying a key fob from ebay, you need to make sure you've got the correct part number and frequency, and you'll need to program the central locking to recognise it (There's a procedure for doing this somewhere on here). You'll still need to use the front section of your fob as this has the immobiliser transponder in it (and reprogramming one of those is very difficult)

Edit: here's the first thread about programming keys I could find

[JAAUDIA6]

Hi Nick, tried the lock/unlock switch on the drivers door with the ignition switched on and even when driving; the lock button locks the car but the unlock button doesn't unlock the car, then I have to open each door manually by the door handle.
In regards to the key, please see attached picture of the butchered key. Any idea now to seperate the two?A6 Key.jpg

[NickPicks]

The bit that's been butchered should have had a nice little slot, which you just lever up with a 4mm screwdriver. Whoever did it before has obviously not realised that and twisted the screwdriver (although it looks like they might have used a soldering iron!)

Here's a link to a video which shows exactly the way mine comes apart: http://www.youtube.com/watch?v=keYT5bXoyNk

[NickPicks]

Hi Nick, tried the lock/unlock switch on the drivers door with the ignition switched on and even when driving; the lock button locks the car but the unlock button doesn't unlock the car, then I have to open each door manually by the door handle.

If the lock button works but not unlock, then the key is communicating, but either the unlock button is not working (might not be contacting on the electronic bit underneath) or the electronics are not working.

[JAAUDIA6]

Hi Nick, re the key; I have managed to get the top casing of the remote part of the key with great difficulty, but the lower half containing the circuit board is stuck fast.
It has been glued with a 2 part epoxy so doubt it will ever come apart. I have oredered a replacement key housing, as soon as I get this I will very carefully prise open the key blade
part once removing the screw of course and then remove the transponder and circuit board to the new housing. I have since tried my key in tha car and it still starts so I know the transponder is preently working. Many thanks for your tips. In regards to the internal switch, I doubt that this will be open circuit, more likely the central locking board is defunct, when I get the new housing will try and sync the key to the car and re-evaluate the situation. Thanks agin for your support.

[JAAUDIA6]

It is the internal lock button NOT the lock button on the key. The key does nothing apart from manually open the car with the key blade and start the car.