Key fob battery URGENT HELP!

I

irfan a8

Member
Hi guys, I had to remove the remote battery from my a2 fob, when battery was replaced it won't sync , open car and lock with key reopen put key in ignition lights on car locks and unlocks at this point it's usually done, but the alarm goes off and won't lock or unlock with remote, so it's not immobilising the car , won't start cuts off. Thanks in advance for any help I'm stuck !!


Irfan
 
I thought you needed to put the keys in the ignition and turn on and then press unlock button then remove keys and press unlock button again to resync a remote fob, as thats how ive done it before, Thow the engine should start as thats done via the transponder chip hidden in the depths of the key.
Id also remove the battery lead on the cars battery in the boot to reset the cccu as may help
 
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Thanks mate, tried that too doesn't work still, is the transponder in the key part of the fob or in the remote unit itself? The car doesn't immobilise and cuts immediately off when you start it.
 
sounds like youv may of mixed up key parts as noticed your message to steve about swapping keys, and parts about , who is the best person to help you, the transponders in the key in a tiny channel next to where the chrome part of the key hinges in the black plastic part, its a tiny black glass tube about 1mm diameter x 5mm long and normally glued in tight, I once put my spare key in without a transponder in and the car starts for 3 or 4 seconds then cuts out took me about 5 mins and 10 restarts to suss id picked up the wrong keys so perhaps youv put the key back in the wrong casing so the transponder and remote dont match your car ..hopefully steve will step in and help you as he knows his stuff
 
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Thanks again, I think you are right as when the battery was removed the key blade part also separated , that's the bit that holds the transponder I think, and I cannot a present find that bit!! I was in a massive hurry when all this happened so was in a panic , long story! I may need a new transponder/chip I will wait for Steve to contact me thanks
 
irfan a8 said:
Thanks again, I think you are right as when the battery was removed the key blade part also separated , that's the bit that holds the transponder I think, and I cannot a present find that bit!! I was in a massive hurry when all this happened so was in a panic , long story! I may need a new transponder/chip I will wait for Steve to contact me thanks
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If the key operates the ignition then unless you had more than one key it should have the transponder that matches it, or did you separate the bits of the key part and swap anything around?


So in short, unless you dismantled the key half of the fob it should work (unless it is a different key half from anothe fob that has never been set up for your car (even though the blade fits).

But getting the remote operation is the first step by putting the key in the ignition, turning it on and pressing the unlock button and then removing the key. if that doesn't work then one of two things have gone wrong. that key fob has never been matched before now, or you have put the battery in the wrong way around (or the battery is dead).

Steve B
 
Hi thanks for your reply , when I took the battery out the key part of it also came apart don't know how , I was actually taking it apart to try the battery in another remote for my Merc so I could get to work!! When I got home I could not find the bit that clips on to keep the key blade secure, that's the bit with the transponder I think, I have looked high and low haven't yet found it!! So need new transponder and what not ?
 
Ok panic over I found the transponder bit that clips onto the blade it had fallen down the side of the seat, its synced back fine again , thanks again for your help guys!!
 
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