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Pete, Mercedes Mechanic
Category: Mercedes
Satisfied Customers: 27930
Experience:  Over 15 years experience as a Mercedes dealer technician
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Im having trouble with my mercedes A class keys, i can start

Customer Question

Customer: Hi im having trouble with my mercedes A class keys, i can start the car as normal however even after trying changing the betteries and tryinmg the resyncronisinjg my keys will still not unlock/lock my car.
JA: Thanks. Can you give me any more details about your issue?
Customer: last night the keys stopped unlocking or locking the car, so today i changed the battery and it seemed to have no effect though the light is comming on on the fob
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Submitted: 1 year ago.
Category: Mercedes
Expert:  Pete replied 1 year ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

If this issue is with one key only/one remote only that is not unlocking or locking the vehicle the most common cause for this here is the remote itself needing replaced.I have seen the remote fail in the past before needing replaced for this issue here.Even though it is starting and turning off the vehicle this is a seperate circuit then the unlocking and locking circuit in the remote/fob.

The red light blinking on the remote/fob only indicates the battery(ies) are o.k.

If this is occuring with more then one remote/fob let me know so we can continue.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 1 year ago.
to answer, yes i have tried the spare keys when they ran out of bettery and i replaced it exactly the same happened.
Expert:  Pete replied 1 year ago.

Was anything done that may have caused the issue here before the fault occured?

Customer: replied 1 year ago.
not as far as Im aware was working fine untill tthe battery ran out both times.
Expert:  Pete replied 1 year ago.

This sounds like both remotes/fobs need resynchronized to correct this here.This is usually done with a dealers SDS machine or a compatible scan tool plugged into your vehicle and can take less then a half hour to do in most cases.If you do not have one of these tools to reprogram them a shop or dealer may have to do this as I do not see a manual way myself for this to be done.

Since this only occured when the battery ran out both times this doesnt sound like a component itself is at fault but more like a fault with programming with them needing synchronized/programmed again.

In some cases holding down the lock and unlock buttons for about 10 seconds next to the vehicle will program them again but usually this will require a dealer or repair center to do this.

Thanks Pete

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