Citroen C8 - keyfob problem

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Sid Tran
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Citroen C8 - keyfob problem

Post by Sid Tran »

Good evening, all!

About a couple of weeks ago, the remote control / keyfob for our Citroen C8 stopped working, so we have been manually locking the doors using the key.

I finally got round to taking the CR1620 battery out, testing it to confirm that it was low / needing replacement and then ordering 2 new batteries.

These arrived today and I have just changed the battery in the keyfob, but it still does not work. Am I supposed to reset / reboot it somehow?

I have done the following

- checked that the new battery is showing good charge
- fitted the battery the right way round
- cleaned the contacts and the rubber buttons with a cotton bud
- fitted eveything back together correctly.

I would be most grateful for any advice.

With best wishes to all
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GiveMeABreak
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Re: Citroen C8 - keyfob problem

Post by GiveMeABreak »

Ok, so once you change the battery you need to resynchronise the key.
Get in the car and close the doors, put the key in the ignition and move to ignition only - don't start the car.
Hold down the locking button on the fob for 5 seconds, then let go and remove the key.
Now exit the vehicle and try locking and unlocking the vehicle with the remote.
Sid Tran
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Re: Citroen C8 - keyfob problem

Post by Sid Tran »

Thank you so much.

I was so excited to try this that I immediately rushed outside.

Unfortunately, I'm not getting much success.

To recap, I unlocked the car using the key. Got in. Closed the door. Inserted the key and turned it so that the dashboard lights came on. Waited for a few seconds for the whirring noise to stop (when the car checks itself). Pressed down on the LOCK button for 5 seconds. Turned the key to off and removed it. Tried the keyfob.

Nothing.

Then, I tried various combinations - holding the LOCK button down for longer - putting the key into the ignition both way round - locking the car manually afterwards and trying the keyfob from the outside.

I have a spare keyfob. But that stopped working years ago after Mrs. Tran threw it against the wall.

Is there anything else I can try?
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GiveMeABreak
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Re: Citroen C8 - keyfob problem

Post by GiveMeABreak »

Ok, so if this is not working, it is quite possible that the micro switches in the fob under the buttons have worn out or detached. This can happen over years with the keys being dropped. If you separate the fob casing, you may be able to see if the switch is damages or missing a small part of plastic. If it is the micro switches these may be able to be purchased and soldered - or I would consider getting a replacement fob.

If you post up your VIN here I will be able to advise of the correct part.
Sid Tran
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Re: Citroen C8 - keyfob problem

Post by Sid Tran »

Dear Marc,

Thank you very much for this - you are so kind!

When replacing the battery, I checked carefully and didn't notice any damage. I used a cotton bud to clean the contacts on both the circuit board and the back of the rubber buttons.

I will find Mrs. Trans old key to try the resetting procedure and also swap around the parts to see if I can discover anything.

In the meantime, I'll send you my VIN via personal message - I hope that this is alright.

All best wishes,
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Paul-R
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Re: Citroen C8 - keyfob problem

Post by Paul-R »

Try pressing a button first and then, keeping the button held in, turning the key to the "ign" position for ten seconds. Might just work.
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Re: Citroen C8 - keyfob problem

Post by Sid Tran »

VF7**************[VIN obfuscated, can be read by forum staff]
Sid Tran
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Re: Citroen C8 - keyfob problem

Post by Sid Tran »

Thank you very much!

I haven't tried this combination yet.

I'll wait for Mrs. Tran to return and will let you know how I get on...
Paul-R wrote:
07 Dec 2018, 11:59
Try pressing a button first and then, keeping the button held in, turning the key to the "ign" position for ten seconds. Might just work.
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GiveMeABreak
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Re: Citroen C8 - keyfob problem

Post by GiveMeABreak »

Ok, so there are 2 part numbers - 649088.
Now this is 82.72 inc VAT from Citroen for the new fob, but with uncut key. Programming will need to be done using Lexia though.

9170S7 is the part number for the other one that may or may not be cut but is £114.85. Citroen will be able to tell you what the exact differences are.

there's one here (in genuine Citroen packing) for £50 - but will need programming and the blade cutting, unless you can transfer the blade from your old one.
https://www.ebay.co.uk/p/Genuine-CITROE ... 1016348036

You will need to find someone that can code these to the car though - Citroen will do this for a charge if you can't find anyone with a Lexia to do it. You will need to code both keys (your spare fob) too, as ALL keys must be coded together int he same session or any that are not will be locked out.
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Re: Citroen C8 - keyfob problem

Post by MikeT »

I've had some successes re-synching fobs (though with other Citroens) and all I'll say is don't give up and keep trying, especially if you know they worked before the battery failed.
It usually takes me several tries (I can be obstinate like that) and I've never worked out why it doesn't always work first time as I follow the same method each time.

I'm pretty sure that the fob's only send a single pulse per button push so can't understand the instruction to "hold for 10 seconds" and tend to push both buttons several times instead. Although it's stated repeated button presses can invoke "anti-scanning" mode in newer Citroens (meaning all fobs will be ignored for 1 minute) it's what's worked for me.

The only failure I've had is with my C3 and I have no idea if that fob has ever worked (though the key has been programmed and will start the engine).
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GiveMeABreak
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Re: Citroen C8 - keyfob problem

Post by GiveMeABreak »

Actually I just realised on the C8 it is a slightly different procedure -

Switch the ignition on and press any of the the transmitter buttons within 10 seconds of the ignition +

Some of the newer systems do require a certain time for it to be pressed and you will often get a beep to confirm synchronisation - but not on the C8.
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Re: Citroen C8 - keyfob problem

Post by GiveMeABreak »

MikeT wrote:
07 Dec 2018, 15:20
I'm pretty sure that the fob's only send a single pulse per button push so can't understand the instruction to "hold for 10 seconds" and tend to push both buttons several times instead. Although it's stated repeated button presses can invoke "anti-scanning" mode in newer Citroens (meaning all fobs will be ignored for 1 minute) it's what's worked for me.


As I'm working an another fob issue Mike - I thought I would just note the procedure for a Xsara Pciasso, that illustrates the point about holding the buttons down:

Xsara Picasso Re-synchronising:
Synchronisation of HF PLIP remote controls
Perform the following operations:
  • Put the HF key to be synchronised in position "ignition +"
  • Press on the locking button (big button) on the HF key
  • Wait between 5 and 10 seconds
  • Release the locking button on the HF key
  • Switch off the ignition with the HF key
  • Wait 3 seconds
MikeT
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Re: Citroen C8 - keyfob problem

Post by MikeT »

If you tune into the frequency you can hear the pulses Marc. Using my C5 & C3 fob, holding down either button produces two short pulses about half a second apart and that's it.
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GiveMeABreak
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Re: Citroen C8 - keyfob problem

Post by GiveMeABreak »

Yes, there are some differences I know - just thought that I'd mention it as listed for reference. :)
Sid Tran
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Re: Citroen C8 - keyfob problem

Post by Sid Tran »

Good morning!

Thank you all for the helpful and informative responses - I'm very grateful.

So, I managed to find the old key and took both apart, swapping the rubber pads, circuit boards and making a note of the combinations.

The good news is that I have now managed to get one functional key fob :cd:

It turns out that one of the components on the circuit board has been displaced.

I hope that the picture below shows this well... Is there any way that I can arrange to get this repaired?

Also, the donor keyfob has a missing piece - the pivot button and spring that allows the keyblade to swing out like a flickknife.
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IMG_20181209_090937 - circled.jpg