A3 TDI: Engine Stalling or Won't Start?

Hello everyone,

I have an A3 TDI from 1997 with 66 kW, which is not modified, and I am very happy with this car.

From time to time, I experience this electronic error:

The engine sometimes doesn't start, and this happens about 2 times a week.
Sometimes, the engine dies while driving on the highway at speeds of around 120 km/h, and this happens about 2 times a week.

Both times, the ORANGE light with the key/car symbol on the instrument cluster blinks during this process, indicating the immobilizer.

I turn the key back, remove it from the ignition, and repeat the starting process. After 1-2 seconds, the engine starts again after the 2nd attempt!

Could it be that somewhere a relay is malfunctioning or a cable is faulty, or that the ignition switch isn't recognizing the key?

Does anyone else have this problem, and can anyone help me? I'm grateful for any advice.

Best regards,
Mac

Search function: Relay 109.

Thanks, guys.
I replaced the relay, and it's working again.
Mac.

"My Arosa SDI diesel engine from 1999 is also stalling. After visiting 7 workshops, I replaced relay 103, but nothing changed. It seems the problem is actually with relay 109, which is located near the fuses. Is relay 109 related to the glow plug system? Hopefully, this will finally solve the problem - thank you."

Look, what Julian wrote in the two posts above yours .