Hello,

 

The buttons on my key fob were wearing out, so I bought a new key fob (a plastic case and blank blade) for £15 from Euro Car Parts, then transplanted the circuit board and blade from the old case to the new one.

 

Now the new fob will unlock the doors, but not disable the immobiliser.   The engine will not start with the new fob (even though it has the circuit board and blade from the previous fob).

 

Electronically nothing has changed - it's the same old circuit board.  The only change is the new plastic case of the fob.

 

There's only two possible reasons I can think of for this:-

 

• The fob (just a plastic case) contains some hidden electronic component the immobiliser needs, or
• The circuit board has lost settings in the half hour while disconnected for the coin battery while I transplanted it to the new case.

 

How do I make the immobiliser re-recognise the same fob chip its been using for years?  Fortunately I've got another working fob and key.

 

Thanks.

 

Lee.

You need to transfer the immobiliser chip from old to new fob. It's in the bit nearest the key blade. Little (delicate!) glass tube.

 Before anything else may be worth putting old fob next to the ignition while using new fob to try starting the car. this will give an indication of possible issue. 

@Wino @KeithCheetham

Thanks - you're both right.

 

I found the parts of the old fob in the dustbin and the glass cylinder RFID device.  It was well glued in so just looked like a lump of black plastic.

 

Holding it close to the ignition started the engine - it has to be really close.

 

Instead of risking breaking the glass by prising it out, I've transferred that part of the plastic shell to the new fob.  It's not an exact fit but it works. 

 

The new fob made out of bits of the old fob opens the doors and starts the engine.

 

Thanks very much.

 

Lee.

 

PS - I've learnt a lot about how modern car security works.

 

I'd read that it was possible program new fobs, and that the new fob I bought would contain a clean circuit board ready to be programmed to my car.  I didn't realise I was buying an empty plastic case.  It was too cheap to be true.

 

Does anyone here know how much Skoda charge for new keys and fobs (programmed and key cut)?  I assumed it would be a fortune so did this myself.

About €250 per key in France & I believe similar in the UK so you have saved yourself a lot of time & grief.

Can you not carefully cut the chip out of the old case with a Dremil or similar, leaving it in its existing surrounding plastic and then just glue into the new case as a new key is an expensive option given you appear to have all the components to create a good key assembly in the new case.

It shouldn't need a dremel...   That is sure to break the glass capsule.  I'd go for a sharp knife and gently cut the plastic to get the capsule out.

Edited 5 June, 20214 yr by skomaz
Alcohol fuelled spelling

49 minutes ago, skomaz said:

It shoujkdnt need acdremel...   

Pop the cork back in now ! 

35 minutes ago, Wino said:

Pop the cork back in now ! 

 

Done as I'm on the beers now...

You'll need to apply something like brake cleaner or acetone (nail varnish remover) to soften the glue before trying to remove the chip otherwise chances are you'll just shatter the glass.

Not ideal but you can disable the immobilizer on the ECU. There are a few places online that will do it by mail order relatively inexpensively.

He got it going already Joe:

 

On 05/06/2021 at 15:04, Lee24 said:

I found the parts of the old fob in the dustbin and the glass cylinder RFID device.  It was well glued in so just looked like a lump of black plastic.

 

Holding it close to the ignition started the engine - it has to be really close.

 

Instead of risking breaking the glass by prising it out, I've transferred that part of the plastic shell to the new fob.  It's not an exact fit but it works. 

 

The new fob made out of bits of the old fob opens the doors and starts the engine.

 

Old post, I know but worth mentioning. 

 

Is OP sure the new case hasn't already fitted with a chip? When I replaced my case, the new (very cheap from eBay) had the immo chip installed. All I needed if I wanted to make it functional was to register the new chip to the car's immo. 

31 minutes ago, makymak said:

Old post, I know but worth mentioning. 

 

Is OP sure the new case hasn't already fitted with a chip? When I replaced my case, the new (very cheap from eBay) had the immo chip installed. All I needed if I wanted to make it functional was to register the new chip to the car's immo. 

Don't you need VAGCAT and VAGCOM/VCDS to do that? It's not impossible with a handy and helpful internet band of brothers but sometimes there's no helpful elf nearby.