2000 Jetta immobilizer issues

I am not sure what they cleaned there, as the immobilizer works in a contactless way.

Your key has a RF transponder chip in it, and the ignition lock has a coil (a ring of wires) on it, which is connected to the instrument cluster.

When you start the car, the instrument cluster initiates the "handshake" with a immobilizer chip, which sits in your key. If it gets an incorrect answer, the warning will blink and after a few seconds the engine will stall. The handshake is done "remotely" in the same way, as in the RF tags. The instrument cluster first inducts some electromagnetic field, which supplies power to the immobilizer chip in your key, then the key sends its code back, which is then received through the same coil.

It could well be, that the read-out coil in the ignition lock is somehow damaged (worn out insulation, broken wire or something similar). Or maybe not the coil itself, but its wires or connectors. This could explain, why it does not work in cold and/or wet.

AFAIK, this coil can be changed separately from the ignition lock and is not very expensive.

I am not a VW mechanic, so I can be wrong.

Hmmm, so there is no chip in the door?

Because another thing that is happening is that my dome light doesnt come on when I open the passenger side door. But it does come on for all other doors. My dealer says its related.

Also, some added information. When I bought this car used, it came with a remote start. Not sure if that adds to the nature of all this.

I just dont want to replace a "chip" for $300.00 and that doesnt take care of the issue.

-Brian

I would say so. Bu again, I am not a VW mechanic.

They shouldn't be related. There is a (hidden) switch in a door lock, which governs the dome light (and a factory alarm if there is one). But it has nothing to do with the immobilizer.

Oh, it is very important. Is this remote start the original VW equipment? Somehow I wouldn't think so. Since you can't start your car without a immobilizer chip, this means, that they needed to get around the immobilizer. And I do not believe that they hacked the firmware of the engine ecu or instrument cluster. It is not that easy.

For example, one of the widely used tricks was to glue the additional immobilizer chip (or the complete key) somewhere near the ignition lock (or just wire the ignition coil to the different place). In this way you effectively disable the immobilizer.

I would bet that this "door chip" has nothing to do with your problem. Myself, I would start looking, if the wiring from instrument cluster to the read out coil is not changed, as there is a good possibility, that it was "modified". Or there is another immobilizer chip glued somewhere near the coil, which is going bad.

Remote start... that maybe creating your problem. What most installers do is tape, glue, tie an extra key under the ignition switch near the reader coil. If that is the case then having both keys present it maybe confusing the immobilizer... especially if they are sending back different codes.

Well that makes sense to me.

But why when it is only cold or damp out. I usually never have this issue during the hot summer days. And I dont use the remote start often.

Thanks Brian