Problems after chan...
 

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Problems after changing car key FOB casing

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My wife's Hyundai Santa key FOBs wore out and I replaced one of them with a new one from Amazon.  The new FOB unlocks/locks the car just fine, the car turns over but it won't start!  There is an immobiliser light flashing on the dash.  Luckily the secondary  physical key will start the car without issue.  If I then switch off the car and try the newly replaced FOB key, it still won't start.  Before you ask, yes I did transfer over the original key to the new FOB casing 🙂

 

Would anyone know what the issue here is and how to resolve?  Thanks


 
Posted : 20/02/2025 9:14 am
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The transponder chip is still in the original case/fob and separate to the circuit board that operates the remote unlocking.


 
Posted : 20/02/2025 9:28 am
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Did you swap over the chip? I believe it's glued in, one way to know is, hold the old key next to the new key, and try and start the car with the new key.


 
Posted : 20/02/2025 9:30 am
cvilla reacted
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The transponder chip is still in the original case/fob and separate to the circuit board that operates the remote unlocking.


 
Posted : 20/02/2025 9:30 am
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I transferred the small circuit board over, is that different to the transponder chip?  The new FOB unlocks/locks the doors electronically but won't start the car.  I have attached a photograph of what is left of the old FOB.

FOB.jpg


 
Posted : 20/02/2025 10:24 am
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That white piece will contain a transponder. Swap that over


 
Posted : 20/02/2025 10:26 am
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Posted by: fossy

That white piece will contain a transponder. Swap that over

Yup, what fossy says.  You can just hold it next to your ign switch to check while you turn the new key, it should recognise the old chip if it's near and disarm the immobiliser.  If it's anything like the one on my MX5, it's hard work to get out of the old key.


 
Posted : 20/02/2025 12:41 pm
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You were correct Fossy but it was a tiny black chip underneath that piece of plastic!  It blended in so well with the casing that it wasn't obvious, at least to my old eyes! Thanks again


 
Posted : 20/02/2025 3:39 pm