Possible faulty intake valve?

Hello everyone,

I have a Seat Alhambra from 2003 with engine code AUY. While driving, it occasionally stalls unexpectedly and then restarts as if it's not building compression. Eventually, it starts running normally again for a short period.
I'm now pressing the intake valve/throttle valve, which serves to turn off the engine. All the vacuum hoses are in good condition.
Has anyone ever experienced a problem like this before?
There are no error codes stored in the system's memory.

Best regards,
Leon.

Theoretically possible Check...

Okay, I checked the valve and it's working perfectly.

The only stored error code indicates a negative deviation in the boost pressure control system.

Okay, so the car always starts perfectly when it's cold. But after a short time, it goes into limp mode, and if you approach an intersection or drive up a longer incline, the engine stalls.
If you try to restart it, the starter motor makes a very easy sound, but after several seconds, it starts up again.

I've now cleaned the valve, it looked really bad. Additionally, I discovered a crack in the vacuum hose between the brake booster and the vacuum pump/diesel pump, and I also replaced it. But there is absolutely no change.
I've noticed that the error seems to increase as the coolant temperature rises.
"Additionally, after restarting following a stall, the tachometer remains at 0 RPM for the first second. Could this be due to a faulty camshaft sensor, or is this normal?"
The second consideration is the diesel pre-pump. What pressure does it need to deliver to the fuel filter? Since there isn't a fuel pressure sensor anywhere along the line, no error code can be stored.
Do you have any other ideas?

Best regards and have a great rest of the week!
Leon.

Relay 109?

It wasn't the relay 109 that was faulty. But it's located in a really inconvenient place on the Alhambra/Sharan.


The problem has been solved; it seems the issue was related to the injection system.
The picture of the clogged pre-pump is attached. It's incredible what you can find sometimes.
A picture of the AGR valve is also included as a bonus.
Thank you very much for your help .

Here's the translation:

"This is what the AGR (Abgasrückführung - exhaust gas recirculation) and everything else looked like from a Polo 9N3 that I had. A piece had broken off and lodged between the piston and cylinder head, blocking the engine."

I would disassemble everything here and verschandeln it thoroughly.

Thank you for your feedback!