A4 2.5 TDI G28 - No Signal

Hi.

Yesterday, I was preparing my silver A4 with an AKN engine for its inspection, so I started the engine, drove it out, and let it idle to warm up.

Suddenly, it starts making a sawing noise, and the filament starts flickering...

Briefly checked, G28 sensor shows no signal, crankshaft position sensor.

I tested two different, identical, and fully functional sensors, but the error persists.

If I clear the error code when starting the engine, the error memory is empty. However, as soon as the engine starts, the error code reappears.

I looked at another engine, and on its flywheel, there were only notches at specific intervals, but no pin or anything like that, which might be broken on my engine.

Three weeks ago, the Audi was still working perfectly.

Where could I start?

Thank you.

Harness and connector?

At first glance, it looks clean... and there are no signs of a weasel or anything like that.

I'm going to use an endoscope to look through the borehole of the G28 this afternoon.

Yesterday, everything was done in a hurry, and I only skimmed the information because of a lack of time.

I just quickly checked the extended measurement blocks using VCDS.
"G28" is displayed more frequently, and for all but one device, a constant speed is indicated.

When the engine starts to stall while idling, the VTG (Variable Turbine Geometry) valve also adjusts.

Unfortunately, there's no news.

Does anyone have any ideas?

Find out the pin configuration of the sensor and check if it needs to be powered by the operating voltage.

I've ordered some documents.

Here's a quick update: I've obtained the original repair manual from that era, a VAG diagnostic tool that connects to the wiring harness of the engine control unit, and the corresponding original wiring diagrams. Now, all I need is the peace, motivation, and time to actually troubleshoot the issue.