Volkswagen Golf 3, 1999, Immobilizer

Hi.
Just a quick question.
How does the immobilizer system manifest itself in the above-mentioned vehicle when the wrong key is used or the signal is not recognized?

No spark when starting.
or
Starts and shuts off after 1 second?
Best regards, Frank.

F B wrote:

Starts and turns off after 1 second?

That's exactly what it is.
Furthermore, one could potentially see an interfering WFS (Working Function Specification) through the diagnosis of the corresponding TCU (Telecommunication Control Unit).

Thank you.
Then it's not the immobilizer that's causing the problem with this car.
It's working again now, after a few failed attempts, as if nothing happened.
The error log is otherwise empty.
I therefore suspect the Hall sensor in the distributor.
He had announced his presence at another polo match in the same way...
Would an error appear in the VCDS log for that?

Best regards, Frank.

F B wrote:

... Would an error appear in the Vcds log file in that case?

If the engine control unit detects the defective sensor: Yes.

"Hall sensor no signal" is generally logged as an error in older MSTG (Motor Steuergerät - Engine Control Unit) systems. This occurs when the ignition is on, but the engine is not running, because the Hall sensor cannot provide a signal in that state. The error can be cleared while the engine is running, but it will reappear after the next start.
"In newer engine control units (ECUs), this 'weakness' has been addressed. Consequently, errors are less likely to occur, even if there is a defect. This is because the ECU, lacking a second sensor, can struggle to distinguish between a situation where the engine is simply off and a situation where the Hall sensor is faulty, as both would result in a lack of signal." Here, manual troubleshooting is required; the error memory is not very helpful.

Yes, thank you, that's enough for my enlightenment.
Wonderful explanation.

Okay, let's just order a distributor, even if we're not entirely sure we need it.
Best regards, Frank.

"Another thing to check would be the ignition coil. We recently had a Passat 35i with an ABS engine that was having this problem – sometimes it would start, sometimes it wouldn't. We replaced the ignition coil, and everything was fine."

Back in the days when I used to drive gasoline cars, I always kept a can of gasoline in the trunk as a reserve.

It was the distributor, or rather, its Hall sensor.
It cost 25 euros at Schrotti's, and the thing is running again.
Thank you.
Best regards, Frank.

Thank you for the feedback!