C5X7 key synchronisation

[Peter.N.]

Just fitted a new battery to one of my keys and can't synchronise i, turns the ignition on but won't open the doors.. In the book it says' put key in ignition, switch on and hold button 'C' down for 10 seconds' doesn't work. Was working OK before I changed the battery but only when it was warm. The other key doesn't work and I have tried the same with that.

Any ideas?

Thanks, Peter.

[wheeler]

Sorry if this sounds very obvious its just i have seen this many times. Is the battery round the correct way & have you confirmed there is not a child safe warning sticker on one side of the battery? lots of these batteries come with these little warning stickers stuck on one side now that need to be removed before fitting.

My preferred method of syncing is to sit in car with all doors closed, switch ignition on & press the lock button rapidly about 8 times then switch off ignition, repeat for any other keys, when the last key is done ignition off, wait 10 seconds & try remotes.

[wurlycorner]

This is a timely posting - I've just put a new battery in one of the keys that came with my X7 and it's not working, but I hadn't looked into what might be needed to relearn. Will give this a go!

[Kees]

Sometimes you need a 4 caracter code and the diagbox to add a key to the car.

[JonC2]

This has happened on my Peugeot 406 and 407 and it turned out that I had a batch of faulty new batteries. They were a well- known leading brand too. I was beginning to suspect the fob or the car transponder, however I tried a different supply of battery and voila, the problem solved. Very hard to verify new batteries by measuring voltage alone. Battery buyers beware. Ps: I also had the problem with a house alarm fob- same problem!

[Peter.N.]

Thanks for all your comments, faulty new batteries was something I hadn't given a thought to. I could try putting the old one back and seeing if it works. I have ordered a couple of new ones just to be of the safe side.

No sticky labels and the batteries normally go + side up which both were. I am not trying to ad a key just get the one I have put a new battery in to work.

Thanks again

Peter

[aerodynamica]

This is what I also experienced just before Christmas. I resynched it many times only for it to not work. But the other key still worked.

Turned out to be the battery contact in the fob was not making a good connection. Mild bending and a bit of contact cleaner and it popped back to life. Still working 2 months later so it's worth a look.

[Peter.N.]

Similar problem I think, I fitted two new batteries in spite of the others reading OK and I now have TWO working fobs.

Peter

[wurlycorner]

I tried the 'relearn' procedure on mine at the weekend, but no joy.
Haven't yet explored the battery (it's a second key so it hasn't been top of my priorities just yet - tempting fate that the first one stops working, of course!)

[Peter.N.]

Its quite easy, you put the key in the ignition, turn it on then hold the 'open doors' button for 10 seconds or so. My second key didn't work until I put the brand new battery in it.

Peter