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· Registered
5 Posts
Discussion Starter · #1 ·
Hello Peugeot Forum members,
I just joined today so apologies if post something in the wrong place.
I have a 4007 with both remote keys not working.
I did a Diagbox fault find and both keys shows synchronisation fault
- B1A08 Key 1 synchronisation fault
- B1A09 Key 2 synchronisation fault

I tried all Daigbox options to repair, clear faults, reprogram keys, resynchronise HF keys but nothing works.

The Diagbox can see when the keys operate but not opening the doors :(

Does ANYONE have any idea how to resynchronise a 4007 remote key to the car?

Thanks in advance

· Registered
88 Posts
keyless entry


I assume from your message that you are reading from the Diagnostic port
OBD2 under the steering wheel, which assumes you can enter the vehicle.

What happens if you try and start the car?

Is the car new you you?
Have the keys ever worked for you?

The reason I ask is that it sounds a little like the keys may from another

There are options in the setup for the vehicle for keyless entry but could you please give more info.

Unfortunately I find that answers on this forum are few and far between....

best wishes
Tony Cross

· Registered
5 Posts
Discussion Starter · #4 ·
Hello Tony,

Thanks for taking the time :)

I have owned the car close to 5 years. Both keys worked fine until recently. Yes I have Peugeot diagbox OBD2.

The mechanical keys can open the door and they start the car - It's only the HF remote that doesn't work. I have tried all manner of "key sync" procedures and battery / BSI resets. I have reprogrammed both keys and the HF remotes - but nothing works.

I have noticed even if I try to reprogram only one of the keys, it always finishes the sequence and shows 2 keys remain programmed (it should delete the second key - but doesn't)

Using the Peugeot diagbox, I can see that both keys are sending a remote HF signal, as the car / OBD2 can see the signal but it keeps showing the "keys not synchronised fault - BA108 and BA109

Any thoughts - much appreciated


· Registered
88 Posts
Wow what an unusual fault. do you have any other issues with the car?
Assuming both remotes failed at once this seems to rule out a remote send issue.

I am assuming you have tried going into Set / System and tried adjusting the settings from the keyless entry option.

As an ex electronics engineer I suspect it could be a fault in the circuit which converts the 315/433mhz RF signal to a digital stream of data.

The if the sync is out, the obvious culprit would be the Crystal in the receiver.
This crystal oscillates at a similar frequency to the transmitter then by a process call superhetrodyne takes out the modulated difference between the frequencies and produces the data, ( by either modulating the frequency or the amplitude FM or AM) which informs the computer in the car to operate the door locks/windows. This sent data rate must match the clock frequency in the receiver.

In your case is seems as if the frequencies may be slightly out causing the sync loss fault code. Crystals are by far the most common item to fail in this type of situation, in my experience the remotes suffered far more than the receivers as they are subjected to more stress, the crystals are also very fragile. I have changed many remote crystals, another issue is the legs are very thin and the wire which attaches the crystals can fracture. In this case a resolder can fix.

Because the car can see a signal being sent seems to indicate to me that the electronics are probably ok.

Are there any other readers who may have a circuit showing this area of the
computer, however sometimes these units are sealed with resin and are simply not serviceable, and are usually bloody expensive to replace.
I know as I replaced one in a friends Mitsubishi 4WD.

If the frequencies were correct you would most likely expect a data match error, such as using the wrong remote.

It sounds like you have tried everything to fix the problem I guess you could get a quote for the module or even a breakers part maybe.

Has anyone else replaced a control board on a 4007?
Not sure if it will just plugin or will you have problems starting?????

good luck


· Registered
5 Posts
Discussion Starter · #6 ·
Hi Tony, it makes sense that you say the receiver on the car might be at fault. If it was the transmitter on the key, then I could expect one key to fail, but not both and at the same time. The common denominator would point to the car / receiver.
I have not tried the keyless entry settings - I will look at that option this evening.
I did speak with a Peugeot main dealer who told me the last 4007 they had in, took them 6 attempts to re-synchronise the keys . . . . . maybe I should also persevere and keep trying to re-synchronise it using the OBD2 diagbox tool. Will let you know how I get on. And thanks again for your thoughts. Mark

· Registered
5 Posts
Discussion Starter · #7 ·
So a quick follow up - I spent an hour using diagbox re/synchronising the keys over and over again. Doing precisely the same thing each time. The procedure was:
- unlock the RF module
- press both key fob buttons for 2 seconds
- touch nothing for 2 seconds
- press the unlock button for 1 second
After many many many times of trying - finally the key sync error disappeared and I now have a working remote key fob!
Final thought - I am still uncertain if it was a hardware issue or flakey software - but all working OK now. Thanks to Tony for your insight ;-)
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