# Jetta won't start after swap HELP!!!



## adamlavigne (Feb 24, 2015)

Hey everyone. I have an '05 jetta 2.5 that I need some help with. The car jumped timing and wouldn't start so I purchased a used engine from LKQ, after the swap the car won't. On the dash, it say immobilizer active! This is due to the computer I think? I was wondering if anyone has any suggestions that I may want to try? 

The donor car is 2007 Rabbit 2.5 VIN number is: WVWBR71K07W059113 -- I am using the ECU and wiring harness from this car.

My car, '05 jetta 2.5 the VIN number is: 3VWSF71K25M637666

The car turns over but does not fire. Any advice is much appreciated.


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## killerbunny (Jul 10, 2008)

If it is the immobilizer stopping it, I believe the ecu is seeing the the key being used as incorrect. I am guessing you are using the original key. If you were able to use the original ecu for your car it should work, whether or not it works with the harness from the newer motor I am unsure about. Another option would be to get the new ecu to recognize the old key, dealerships should be able to it but they might charge a hefty fee. Another option would be to get the immobilizer defeated/deleted by an aftermarket tuning company. I think united Motorsports will do it. Also iirc when the immobilizer is active it will throw a code, see if you can scan for a code to verify that it is indeed the immobilizer that is causing the issue.


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## granth (Dec 5, 2001)

A couple issues here... First, Immobilizer:

The ecu must be paired with the keys, and also with the cluster. Like the ecu, the cluster has immobilizer codes, and if it doesn't match the ecu, immo will activate. The dealer might be able to pair them for you, but it would likely require some begging/bribing. I'm fairly certain that non-matching keys will still start the car, but it will turn off after a couple minutes and flash the immo cel. I'm guessing it's the unmatched cluster that is preventing your car from starting. 

Now let's talk ecu's:

The ecu must match your engine. For example, a california-emissions ecu will throw cel's about missing o2 sensors on a non-cali-emissions car. Also, an auto-trans ecu will run poorly on a manual-trans car. A dealer or skilled tuner *might* be able to adapt the ecu to your engine, but it's highly recommended to find a perfect match to start with. The ecu code can be found on the ecu casing. For example, my '08 non-cali rabbit with manual-trans uses ecu "07k 906 032 BK". The last two letters are the variant code and it's essential that they match.


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## adamlavigne (Feb 24, 2015)

*Update*

Well I'm using the computer from the '05 and the car is now starting... had a fuse issue. The car will run and start for roughly 30 seconds... I replaced the fuel pump, fuel filter made sure all 3 of the fuses are good, have good gas (93) and it still stalls. The only time I hear the pump kick in is when I remove the battery cable and replace and open the drivers door is the only time I hear it kick in. I have to do this 5 or 6 times until it has enough gas for the car to start.. If i check it on the fuel rail there is no presser built up, not sure what the issue could be? 

Any ideas what could be going on?


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## granth (Dec 5, 2001)

Is IMMO / CEL still active!? 

Have you scanned the car?


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## adamlavigne (Feb 24, 2015)

granth said:


> Is IMMO / CEL still active!?
> 
> Have you scanned the car?


I have I'm getting the following codes now: P0037 p0102 p0627 p0030 p0864


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## granth (Dec 5, 2001)

Did you check the part number on your ecu's? Post both old and new. Eg. 07k 906 032 BK

At least one of those codes are regarding o2 sensor. Cali-car ecu?


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## adamlavigne (Feb 24, 2015)

granth said:


> Did you check the part number on your ecu's? Post both old and new. Eg. 07k 906 032 BK
> 
> At least one of those codes are regarding o2 sensor. Cali-car ecu?


05 ecu (the one I'm using) 06a 906 032 qe

07 ecu (this came with the new engine ) 07k 906 032 s


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## adamlavigne (Feb 24, 2015)

I think there is a short somewhere. .. when I use a simple electrical tester the one with the light bulb... I hold the tester to the fuse for the fuel pump and hook up the battery and it has power. But after that initial time I don't have power. I took a wire from another location and touched it to that fuse and I had the power. The car ran... not sure if it's a short, a relay the ecu or what the issue is?


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## granth (Dec 5, 2001)

Weird that your original ecu has the 06a product code. Isn't that the 1.8T engine code?


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