I.ve got an audi a4 2004 plate.changed the battery in the remote keys and now it wont work unless i lock or unlock it maually.tried re sync from the manual but still no joy. can you help

more than likely as the fob key has a chip that syncs with the security system etc , have you got the owners handbook as this should give you the procedure that needs to be carried out to reset the fob key,can't take the credit for this fix as found it at an audi forum give it a try .
I learned a new trick tonight. I recently changed the battery in my key and it would no longer open the door locks. I just sat down and read the manual and found that if you replace the battery you need to re-synch the key.

Here is how it's done.

replace the battery. ( pry open the little tab at the seam in the key, then split the bottom in two with your finger)

Press the lock or unlock button once.
with-in one minute put the key into the drivers door and lock and unlock it manualy.

TADA it works again

I have seen a few threads and questions that said there fob stopped working. so I thought I would throw this out there. I hope that some of you with this problem that don't have manuals because the previous owner kept it for a souvenir will find this Helpful.

Try to jerk steering Wheel and turn key in same time

You either have a dead battery in the remote or the key has become deprogrammed. Try replacing the battery, if that doesn't work you may have to have it reprogrammed at the dealer.

what type of vehicle?

you should be able to unlock car with manual key, try on passenger door lock

unlock the car with the key and hold the key over for 30 secs,(the windows will go down) then lock the car/hold key over for 30 secs,(the windows will go up). wait 30 secs then press/hold down the unlock button on the key fob,this will resyncronise the alarm/key fobs.

hi well this is a bit long so if you can bare with me i will try explain how to , clear system to decode, and recode as this is what it sounds like that the coding has gone from the ignition key....ok here goe's
to sync key with car depress lock or unlock button manually lock the drivers door within 30 seconds of the above system should now work....if not do next bit
switch ignition on ( using non chip key ) manually lock drivers door using key ( another one, hopefully you will have more than one) press unlock button 5 times, in one second intervals indicators flash 5x for every time signal is received switch ignition off and remove key
that's the de-programming done...
to de-program the system if above fails..........
switch ignition on ( use key without remote ) manually lock drivers door using key to be synced with car complete the following within 30 seconds of doing above within 5 seconds press the unlock button on key indicators should flash once wait 5 seconds press unlock button once to confirm programming vehicle should unlock this also will confirm deactivation of programming mode switch ignition off remove key..that should be it, then try new programed key in ignition.

to re-program system and sync with key switch ignition on manually lock drivers door using key ( another one, hopefully you will have more than one) press unlock button 5 times, in one second intervals indicators flash 5x for every time signal is received switch ignition off and remove key
that should be it, if no joy then will have to main dealer i am afraid...hope this helps

unlock the car with the key/hold over for 30 secs.
lock the car with the key/hold over 30 secs.
then press/hold down unlock button on remote.
you have just reset your alarm/central locking system
change remote batteries every 2 years...... both remotes....

unlock car with key/hold over for 30 secs then lock car with key/hold over for 30 secs then unlock with remote hold button down for 30 secs.this should reset system.

place key in ignition turn ignition to run position
hit the butons on remote it should re prog the remote
if remote got wet or dirty open up remote and clean contacts