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I bought a 2002 Jetta TDI a few months ago. Wonderful car, enjoy driving it, but only have a valet key for it, the master key was NOT available. I've thought about getting a second key made, just in case, but am a bit confused by the transponder system.

From my reading, there's a chip in each key, and the code on the chip is read by the car using a coil in the steering column. To unlock the steering and start the car, you need a key that has been cut to match the car. To keep the engine running, you need the chip to be recognized by the cars computer system.

I've seen blank keys available for less than $50, and apparently they can be cut to match the car by providing the VIN and/or photos of an existing key, so getting a physical key doesn't seem to be too much of a problem.

Getting the new key code into the computer apparently requires a dealer or locksmith, so that's an extra expense.


First question: What happens if the car battery runs down or has to be disconnected to service the engine or to replace the battery? Does the computer lose all the codes? That would make the car inoperable and probably require a tow to a dealer! Seems unlikely, but.....

Second question: If I get a new key cut, but NOT programmed into the car, it could still be used to unlock the door and to work the ignition switch. If my current key was close to the steering column (but not in the switch), would that allow the car to start and run? In other words, how close to the steering column does the coded key need to be to be read?

third question: Relay 109 seems to be the main ON/OFF control for just about everything that makes the engine run... If I used a non-programmed key to unlock the door and to work the ignition switch, would bypassing the relay contacts with a switch allow the engine to run? I'd have to turn the switch off to kill the engine, but that would be a small price to pay if it would defeat all the programming nonsense!....
 

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1: It's stored somehow so it's not effected. I've heard that it's sometimes tripped but I don't know why.

2. The unprogrammed will unlock the doors by key and start the engine. It's just that the engine will immediately shut off. That lets you know it's the immobilizer and not a starter problem.

3. Relay 109 provides power to the ECU. The immobilizer control is built into the ECU programming. Separate things.
 

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Welcome to the forum. welcometomyturbodies

Now I've heard of valet keys before on here and they didn't explain what they are. Is it just a blank key without the fob?

I spare key is a must if you only have one but they can be expensive around £200 then you have to have it programmed to your system.

If the battery is disconnected for what ever reason then reconnected or replaced it doesn't delete all the ecu setting, thats what the dealer told me when I wanted the radio code. As for the radio code you only need it if you put the radio into another VW. I did get the code of them.

I asked about a spare steel key as I've always carried a spare for all the cars I've had. VW don't make them you have to buy a new one. I asked at the locksmith and they can get blanks and cut them to match my key but the physical size is the same as the standard key so it no advantage to carry 2 keys with you at all times. Yes blanks are about £15 over here. ;)
 

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Thanks for the information!

good to know that the stored code for my key won't be lost if/when the battery is disconnected!

As for getting a second key... from my searching, I've found places that will provide and cut the blank for around $50, which seems a little steep, but probably better than having the car towed somewhere if I lose my only key!....

Getting a second key programmed into the car's computer looks to be around $100, which is outrageous even in our economy!... Apparently, doing that requires a special "secret" code, which of course I wasn't given...

My current thinking is this: my existing key can be opened (I've done that) and I can see the little RFID capsule that responds to the immobilizer. I'm planning to remove it and fasten it to the steering column next to the keyslot, using a glob of silicon sealant to hold it in place and protect it. I will then have another key cut but not programmed, and find some place to mount it on the car where I can reach it in an emergency. Or maybe just open it and remove the metal key itself, which I can carry in my wallet.

Since the RFID chip is always available, I shouldn't have to program the second key in. Yes, it defeats some security, but I've always figured that if someone wants a car badly enough, they will get it anyway.... and this way, I won't be stranded someday!...

By the way, I looked in the trunk and next to the spare tire, stamped into the metal of the tirewell is a 4-digit code (4001), which MIGHT be my super-secret key code! .....
 

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Gluing the immobilizer chip will work. However, I'd glue it to the inside of the trim so you can't accidentally bump it off. You didn't get the SKC because they stopped giving them out after 2001. Now even the dealer doesn't see them. The encrypted code goes from the an internet server straight to the diagnostic tool.
 

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There are vag tech tools that will get the code from the car for the key is it then possible to make it so the new key can also start the vehicle??
 

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So vag tacho is what is needed correct?, is there a specific version that is needed to work.. I have a 03 Jetta Wagon.. There are many different versions on ebay
 

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No issues here; but I use AVG. If you're a licensed Avast user, you might want to shoot their support an e-mail and ask them to look at that file. False postives are not at all unusual these days; we've had users report them on several occasions with older VAG-COM versions, and upon contacting their anti-virus supplier, they were told it was a false positive.

-Uwe-
 

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Well I've just tried it on my desktop WinXP with Avast and it picks it up the same. I disabled Avast and downloaded then scaned it again and it picks it up. Now I've search the help but I can't see any options for reporting false positives with Avast 5, yes I'm a registered user. When I use Avast 4.8 and it found something you get the report box clean, delete, send to virus chest, ignore etc and there was a button to report as false positive.

I'm a member if the Avast Forum so I'm going to ask this question.

Which anti-virus are you using bagdwag? ;)
 

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I download and then get to vagcom.exe and when I try to open that it says I do not have access to it? What am I doing wrong?
 
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