Fixed car fab sync issue 2015 Cupra

Aug 26, 2019
So my fob stopped working after changing the battery recently. The battery was only low but when I put the new battery in and it didn't work at all. I decided to put the old battery back in and to my surprise it still didn't work! Thinking there was a particular technique to changing it, I gave it to the Seat dealer on my last service. They changed the battery and it still didn't work. It was my spare fob so wasn't massively concerned but when my main key battery indicated as low on the car display recently, I started to worry. I called Seat and asked if there was a technique to changing it and they said no, just swap with the new battery in my old fob. I asked how much it would cost to fix my old fob and they said £82 to diagnose it or £76 to reprogram it! Ouch, off to the forums I went!

Okay so long story short, swapped the battery and it worked. Checked forums for a fix for my old fob and couldn't find anything. I found a way to resync it in the manual and after 2 mins it worked fine.

Remove the key cover on the door handle, with the door unlocked, press lock on the fob then lock the car manually with the key (within 1 min). Then (and I had removed the key from the door) press unlock, insert ket and manually unlock. Key was resynced and now works fine.

Why Seat dealer couldn't do this and wanted to charge me to diagnose, we will leave for another thread!

Anyway, hope this helps a few of you that are struggling. The manual did say the key can become unsynced if the Button is pressed multiple times when out of reach of your car, and obviously in some occasions when the battery is changed, maybe by inadvertently pressing the buttons when doing it.
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Active Member
Mar 10, 2013
If you look at the other VAG MQB platform marques, then there is a key fob battery change procedure. I can’t find the equivalent in the Leon workshop manuals (in the guide sections).

However, when you remove the battery, you are supposed to press one of the fob buttons prior to inserting the new battery. This is supposed to calibrate the key to acknowledge the new battery. Even though the image is for the previous style key, the Mk3 Octavia has the same key as Mk3 Leon.


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