# ECU Swap and Immobilizer...Can VAG-Com Defeat It?



## Raek (Aug 1, 2003)

So, I had to do a wideband conversion when going Frankenturbo. Everything was good until I went to get a new key cut at the dealership. They went to program the key, and since I'm running a MKIV Jetta ECU, it triggered the immobilizer.

My key fob clearly doesn't communicate, and I have the annoying little immobilizer light flashing. All. The. Time. 

A friend of mine as VAG-Com, but is under the impression that it can't be defeated due to the swap. Is he right? I think it's been mentioned that it doesn't matter somewhere on another thread, however...I wanted to condense it to this one.

Anyway, I need to get the car inspected...and, while I know the immobilizer won't have any affect on the inspection, I'd like to show up light-free on my cluster. It's a matter or presentation...hahaha.


Thanks in advance, guyyyyyys :heart::heart::heart:


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## Silver TT (Jan 26, 2015)

Hmm.... 

What year is your car? 
Do you know what year the ECU was out of (or part number)? 
Do you know if your car is originally IMMO3 or IMMO2, and what is the new ECU? 
just to be clear, the car drives, but the light flashes all the time? 
Were you getting a key cut, or having the original key re-programmed?

I know that you can't defeat the immobilizer with vag-com. How are you planning on tuning the car? You can defeat it with Maestro. 
Let me know if you get it figured out, I'm doing the same thing soon.
Thanks


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## Raek (Aug 1, 2003)

I have to check out what gen Immo it is...the car is an 01. Need to also check the year of the ECU...but, I believe it may be an 01 as well. I think 01 Jettas were wideband.

I actually got a new key cut. When the service guy came back (he was well aware of Frankenturbo and such. He's a Vortex guy), he said it couldn't be programmed due to the swap...I think the paperwork actually has the ECU p/n on it. 

The car has a Maestro tune, so maybe I can contact FFE and see what they can do.


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## Silver TT (Jan 26, 2015)

The Ross Tech website says that '01 Jetta's can be either IMMO 2 or 3. Sounds like a mismatch between the cluster gen and the ECU. But if the car is running, FFE probably disabled some portion of the immobilizer, and may just need to disable the light... 
Keep me posted.


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## 20v master (May 7, 2009)

01 TT and 01 Jettas both should be able to have Immobilizer matched with VAG COM, it was in 02 that they went to Immo 3 that can't be done via VAG COM. I think this is accurate, it's been a LONG time, but this info should be on Ross Tech's website somewhere.


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## formerly silveratljetta (Feb 6, 2007)

The simplest solution seems to be send the ECU out to have the immobilizer defeated.


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## lite1979 (Sep 9, 2005)

I have a 2001 with Immo3, FYI. I had to narrow my cluster search to a few thousand VINs when I replaced it for that reason.


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