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When I got in my '04 VW Jetta the other day, the car wouldn't start and the immobilizer light was blinking. I tried charging the battery, pulling the terminals from the battery, and leaving the key turned to "on" for a half hour (as many people online suggested). Nothing worked, on all three keys. I figured I'd take it to the dealer this weekend.

Then I got in my car today to grab something and put my key in on a whim. The immobilizer light didn't come on, so I started it and it ran just like normal. I don't understand how this happened, but we're planning a road trip in three weeks and I'd very much not like to be stuck at a gas station in the Tennessee mountains if this happens again.

So what happened to trigger the immobilizer? Why wouldn't it turn off? And is it likely to happen again?

EDIT: Well, the immobilizer is on again. After stopping at a Speedway to get gas, the car won't turn on.

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2 Answers 2

up vote 0 down vote accepted

There are "induction coils" all over the place in a modern vehicle doing measuring jobs for the various systems involved. In the steering lock/columm assembly, there is an induction coil which reads the coding on the cars key(s) and allows the immobilser to be turned off. If this coil fails in any way the immobiser stays active.

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Upon further discussion with the dealer, it sounds like the wiring harness in the steering column had been somehow severed, and a short in the induction coil in that assembly was what was causing the immobilizer to fire. Thanks for the answer! –  ilinamorato Nov 19 '13 at 16:51

Well, we took it to the dealer. Turns out it was the induction coil, but I don't know how that's possible. If anyone can explain that, I'll make that the accepted answer. Thanks!

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